Affinage

CD81

CD81 antigen · UniProt P60033

Length
236 aa
Mass
25.8 kDa
Annotated
2026-06-09
100 papers in source corpus 47 papers cited in narrative 48 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CD81 (originally TAPA-1) is a four-pass transmembrane tetraspanin that acts as a cell-surface molecular scaffold, organizing partner proteins into discrete complexes that govern immune cell signaling, cell adhesion and motility, and serve as portals for pathogen entry (PMID:1695320, PMID:1860863, PMID:11087758). Its defining biochemical feature is an allosteric large extracellular domain whose conformation is controlled by an intramembrane cholesterol-binding pocket: cholesterol binding switches the ectodomain between 'open' and 'closed' states that tune partner-network assembly and viral receptor activity (PMID:32900848). In B cells, CD81 partners with CD19 through reciprocal ectodomain contacts, and a cryo-EM structure shows that CD81 opens its ectodomain to expose a hydrophobic CD19-binding surface and reorganizes its transmembrane helices to occlude the cholesterol pocket upon engagement (PMID:33446559, PMID:7690834, PMID:32338599); through this interaction CD81 is non-redundantly required for trafficking the mature, post-ER glycoform of CD19 to the plasma membrane (PMID:14530327). Loss-of-function CD81 mutation in humans abolishes surface CD19 and causes antibody deficiency, with retroviral CD81 rescuing CD19 surface expression (PMID:20237408). Beyond CD19, CD81 forms surface complexes with Leu-13, HLA-DR, CD21, FPRP/CD9P-1 (EWI-F), α4β1 and αV integrins, claudin-1, and PI4K type II, and signals through inducible palmitoylation, 14-3-3ε association, and Syk-dependent ezrin/ERM phosphorylation to regulate BCR and TCR signaling, immune synapse maturation, actin remodeling, and cell motility (PMID:2398277, PMID:8409388, PMID:8757325, PMID:9006891, PMID:11087758, PMID:15161911, PMID:14966136, PMID:19654214, PMID:23858057). It serves as a critical post-attachment receptor/co-receptor through its large extracellular loop for hepatitis C virus, partnering with claudin-1 in entry complexes, and is required for Plasmodium sporozoite and influenza virus infection (PMID:14722300, PMID:18337570, PMID:12483205, PMID:24130495). CD81 also directly binds SAMHD1 to promote its proteasomal degradation, raising dNTP pools and HIV-1 reverse transcription (PMID:28871089), and couples αV integrins to FAK signaling to drive irisin-responsive beige adipocyte biogenesis (PMID:32615086).

Mechanistic history

Synthesis pass · year-by-year structured walk · 25 steps
  1. 1990 High

    Established CD81 as the founding-type member of a new four-transmembrane protein family, defining the structural class that frames all later mechanism.

    Evidence cDNA cloning and sequence/topology analysis with immunoprecipitation

    PMID:1695320

    Open questions at the time
    • Sequence homology to CD37/ME491 noted but no functional activity assigned
    • No partner or ligand identified at this stage
  2. 1991 High

    Resolved the membrane topology, placing N- and C-termini cytoplasmic and locating the antigenic/functional epitope in the large second extracellular loop — the surface later shown to mediate partner and viral interactions.

    Evidence In vitro translation into microsomes with limited proteolysis and epitope mapping

    PMID:1860863

    Open questions at the time
    • Does not address conformational dynamics of the loop
    • No high-resolution structure
  3. 1990 High

    First demonstrated CD81 as a scaffold forming a defined surface complex (with Leu-13), introducing the molecular-organizer concept.

    Evidence Reciprocal co-IP in mild detergent with co-modulation and growth-inhibition assays

    PMID:2398277

    Open questions at the time
    • Functional consequence of the complex undefined
    • Stoichiometry unknown
  4. 1993 High

    Dissected the CD19/CD21/CD81 B-cell coreceptor, mapping CD81-CD19 contacts to extracellular domains and assigning CD81 the homotypic-aggregation function, establishing CD81 as the organizing subunit of the BCR coreceptor.

    Evidence Domain-swap chimeras with Ca2+ flux, PI3K co-precipitation, adhesion, and HLA-DR co-IP

    PMID:7690791 PMID:7690834 PMID:8409388

    Open questions at the time
    • Mechanism of CD19 surface delivery not yet defined
    • Structural basis of contacts unresolved
  5. 1993 Medium

    Showed antibody engagement of CD81 triggers tyrosine phosphorylation, an early step driving an antiproliferative signal, providing first evidence of CD81 transducing signals.

    Evidence Tyrosine phosphorylation assays with kinase inhibitors and thiol manipulation in B cells

    PMID:7688390

    Open questions at the time
    • Kinases and direct effectors not identified
    • Thiol dependence mechanistically unexplained
  6. 1997 High

    Linked CD81 to integrins (α4β1, α3β1) and to PI4K type II in peripheral focal complexes, defining an integrin-tetraspanin signaling axis distinct from FAK-based adhesion signaling.

    Evidence Reciprocal co-IP with adhesion-deficient integrin mutants and enzymatic PI4K assays

    PMID:8757325 PMID:9006891

    Open questions at the time
    • How CD81 modulates PI4K activity unresolved
    • Downstream lipid product roles not mapped
  7. 2001 High

    Identified FPRP/CD9P-1 (EWI-F) as the dominant, near-stoichiometric direct partner of CD81, defining the core stable tetraspanin partner and mapping the interaction to the large loop / fourth TM region.

    Evidence Immunoaffinity-MS, cross-linking, gel filtration, chimeric domain mapping, methyl-β-cyclodextrin

    PMID:11087758 PMID:11278880

    Open questions at the time
    • Functional output of CD81-FPRP complex not defined here
    • Cholesterol-independence vs raft role only partially addressed
  8. 2002 High

    Revealed CD81 as a host entry factor for Plasmodium sporozoites, extending its scaffold role to pathogen infection and parasitophorous vacuole formation.

    Evidence CD81-KO mice in vivo/in vitro infection plus antibody inhibition for two Plasmodium species

    PMID:12483205

    Open questions at the time
    • Direct parasite ligand of CD81 not identified
    • Molecular role in vacuole formation unresolved
  9. 2003 High

    Defined CD81's negative control of cell-cell fusion and its non-redundant requirement for delivery of mature CD19 to the B-cell surface, mechanistically distinguishing CD81 from CD9.

    Evidence CD9/CD81 double-KO fusion phenotypes; CD81-KO B cells with endo-H glycoform analysis and rescue transduction

    PMID:12796480 PMID:14530327

    Open questions at the time
    • Trafficking machinery linking CD81 to CD19 export unknown
    • Mechanism of fusion suppression incomplete
  10. 2004 High

    Established CD81 as the HCV entry determinant via its large extracellular loop, converting resistant cells to permissive and defining a post-attachment function.

    Evidence siRNA, gain-of-function expression, chimeric CD9/CD81 domain mapping, neutralizing antibodies, HCVpp

    PMID:14722300

    Open questions at the time
    • Co-receptors not yet defined
    • Step of entry blocked by CD81 not precisely placed
  11. 2004 Medium

    Connected CD81 signaling to inducible palmitoylation and 14-3-3ε binding, providing a redox-sensitive switch that stabilizes coreceptor rafts and amplifies BCR signaling.

    Evidence Metabolic palmitoylation labeling, cysteine mutagenesis, raft fractionation, co-IP under oxidative conditions

    PMID:14966136 PMID:15161911

    Open questions at the time
    • Palmitoyl transferase not identified
    • Functional role of 14-3-3 recruitment downstream undefined
  12. 2005 Medium

    Mapped the HCV E2 residues (Y527, W529, region 3) that bind CD81 versus those affecting infectivity independent of binding, refining the receptor interface.

    Evidence Alanine-scan mutagenesis of E2, CD81-GST binding, HCVpp infectivity

    PMID:15670777 PMID:16943299

    Open questions at the time
    • Species selectivity of LEL not fully mechanistically explained
    • Full-length CD81 supporting infection across species unresolved
  13. 2008 Medium

    Identified claudin-1 as a heterotypic CD81 partner in HCV coreceptor complexes and mapped the CD81-CLDN1 molecular interface, defining a post-attachment entry machine.

    Evidence FRET in live cells/tissue, structure-guided CD81 mutagenesis, HCV infection assays

    PMID:18337570 PMID:22897233

    Open questions at the time
    • Dynamics of complex reorganization during entry partly inferred
    • Role of homotypic vs heterotypic clustering unresolved
  14. 2009 High

    Linked CD81 engagement to Syk-driven ezrin/ERM phosphorylation and actin remodeling, and established CD81 as a negative regulator of BCR signaling, reconciling its scaffold and signaling functions.

    Evidence MS phosphoproteomics, Syk inhibition, co-localization in B/NK cells; KO B-cell signaling with BM transplant

    PMID:19654214 PMID:19737782 PMID:19830727

    Open questions at the time
    • How scaffolding produces negative vs positive signaling outputs context-dependent
    • Direct CD81 cytoplasmic effectors of Syk activation unknown
  15. 2010 High

    Provided definitive human genetic proof that CD81 loss abolishes surface CD19 and causes antibody deficiency, with CD81 rescue restoring CD19, cementing the obligate CD81-CD19 relationship.

    Evidence Patient homozygous mutation, flow cytometry, retroviral rescue, BCR stimulation

    PMID:20237408

    Open questions at the time
    • Structural basis of CD19 dependence not yet defined at this stage
  16. 2010 Medium

    Showed MARCH ubiquitin ligases and microparticle release control CD81 surface levels post-transcriptionally, defining its trafficking and turnover.

    Evidence SILAC proteomics with MARCH over/knockdown; microparticle transfer assays and clathrin/dynamin-dependent endocytosis

    PMID:12421929 PMID:21151997 PMID:22318146

    Open questions at the time
    • Cytoplasmic-tail-independent internalization implicates unidentified partners
    • Physiological triggers of microparticle shedding unclear
  17. 2013 High

    Defined CD81's role in T-cell immune synapse organization through dynamic CD81-CD3-ICAM-1 interactions required for sustained TCR signaling, generalizing the scaffold function to T cells.

    Evidence FRAP, FLIM-FRET, TIRFM, phosphorylation assays, CD69/IL-2 readouts with CD81 KD

    PMID:23858057

    Open questions at the time
    • Direct CD81 binding to CD3/ICAM-1 vs indirect organization not fully separated
  18. 2013 Medium

    Extended pathogen biology by showing CD81 acts at two influenza stages — endosomal fusion and budding-site assembly — broadening its viral-cycle roles.

    Evidence siRNA KD, single-particle live imaging, EM of budding virions

    PMID:24130495

    Open questions at the time
    • Molecular interactions of CD81 with viral proteins not defined
    • Mechanism of budding scission defect unresolved
  19. 2016 Medium

    Mapped CD81's EC2 helices A/B to the RGD-binding site of αVβ3 integrin, providing a direct structural basis for tetraspanin-integrin coupling.

    Evidence Adhesion assays with cRGDfV/7E3 blocking, docking, EC2 lysine mutagenesis

    PMID:27993971

    Open questions at the time
    • Functional consequence of EC2-integrin binding in cells not fully tested here
    • In silico interface not crystallographically confirmed
  20. 2017 High

    Uncovered a non-scaffold function: CD81 binds SAMHD1 and drives its proteasomal degradation, raising dNTP pools and enhancing HIV-1 reverse transcription.

    Evidence Co-IP, bidirectional CD81 manipulation, dNTP measurement, proteasome inhibitor, C-terminal deletion mutant

    PMID:28871089

    Open questions at the time
    • How CD81 routes SAMHD1 to proteasomal degradation mechanistically unclear
    • Whether ubiquitin ligase involved unidentified
  21. 2018 High

    Defined the primary-hepatocyte CD81 interactome (CAPN5, CBLB) supporting HCV entry, distinguishing virus-specific from Plasmodium-specific partner requirements.

    Evidence Quantitative interactome proteomics, CAPN5/CBLB KO, multi-genotype HCV and Plasmodium entry assays

    PMID:30024968

    Open questions at the time
    • Biochemical role of CAPN5/CBLB in entry not mechanistically resolved
  22. 2020 Medium

    Established the allosteric logic of CD81: an intramembrane cholesterol pocket controls an open/closed ectodomain switch that tunes HCV receptor activity and partner-network assembly.

    Evidence Cholesterol-pocket mutagenesis, MD simulations, HCV infection, interactome analysis

    PMID:32900848

    Open questions at the time
    • Conformational model not yet validated by experimental structure at this stage
    • Physiological cholesterol regulation unproven
  23. 2020 High

    Expanded CD81 into metabolic physiology, showing it complexes with αV integrins to relay irisin via FAK signaling for beige adipocyte biogenesis, with loss causing obesity and insulin resistance.

    Evidence scRNA-seq, co-IP, FAK assays, irisin stimulation, CD81-KO metabolic phenotyping

    PMID:32615086

    Open questions at the time
    • Direct irisin receptor identity vs CD81-integrin role not fully separated
  24. 2021 High

    Provided the definitive structural mechanism: cryo-EM of the CD19-CD81 complex shows CD81 opens its ectodomain to expose the CD19-binding surface and reorganizes TM helices to occlude the cholesterol pocket, unifying the allosteric and CD19-trafficking models.

    Evidence 3.8 Å cryo-EM with bound Fab; complementary CD19-interface mutagenesis and 5A6 epitope masking

    PMID:32338599 PMID:33446559

    Open questions at the time
    • Structures of other CD81 partner complexes lacking
    • Dynamics of switching in living membranes not directly observed
  25. 2022 Medium

    Extended CD81's adhesion-scaffold role to cancer: CD81-CD44 ectodomain interaction promotes tumor cell clustering and metastasis, and CD81 supports HRR via Rad51 nuclear translocation conferring radioresistance.

    Evidence Interface-guided mutagenesis with in vivo metastasis models; CD81 KD with γ-H2AX, nuclear Rad51 IF, B02 epistasis

    PMID:33919192 PMID:36193887

    Open questions at the time
    • How surface CD81 controls nuclear Rad51 mechanistically unclear
    • CD44 interaction interface only modeling-predicted

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the cholesterol-gated open/closed conformational switch selects among CD81's many partners (CD19, integrins, claudin-1, SAMHD1, CD44) in different cell types remains unresolved, as does the link between surface scaffold functions and nuclear/cytoplasmic activities.
  • No structures of CD81 bound to integrins, claudin-1, or SAMHD1
  • Mechanism coupling surface CD81 to nuclear Rad51 unknown
  • Determinants of context-specific partner choice undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 4 GO:0001618 virus receptor activity 3 GO:0008289 lipid binding 2 GO:0098772 molecular function regulator activity 2
Localization
GO:0005886 plasma membrane 4 GO:0005768 endosome 3 GO:0031410 cytoplasmic vesicle 3
Pathway
R-HSA-1643685 Disease 5 R-HSA-162582 Signal Transduction 4 R-HSA-1500931 Cell-Cell communication 3 R-HSA-168256 Immune System 3
Partners
CD19CD44CD9P-1CLDN1ITGA4ITGAVSAMHD1YWHAE
Complex memberships
CD19/CD21/CD81 B-cell coreceptor complexCD81-CAPN5-CBLB complexCD81-CD9-FPRP/CD9P-1 complexCD81-claudin-1 HCV coreceptor complex

Evidence

Reading pass · 48 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1990 CD81 (TAPA-1) is a 26 kDa cell surface protein with four transmembrane domains; the deduced amino acid sequence shows strong homology with CD37 and ME491, placing it in a new family of transmembrane proteins (tetraspanins/TM4SF). cDNA cloning, amino acid sequence analysis, immunoprecipitation Molecular and cellular biology High 1695320
1990 TAPA-1 (CD81) is physically associated on the cell surface with Leu-13 antigen; the two molecules form a complex detectable by co-immunoprecipitation in mild detergent (CHAPS) and can be reciprocally co-modulated by their respective antibodies. Co-immunoprecipitation (CHAPS detergent), co-modulation assays, growth inhibition assays Journal of immunology High 2398277
1991 TAPA-1 (CD81) has a four-transmembrane topology with cytoplasmic N- and C-termini and two extracellular hydrophilic loops; the antigenic epitope lies within the second (large) extracellular domain, established by proteolysis of in vitro translated protein embedded in microsomal membranes. In vitro translation, microsomal membrane insertion, limited proteolysis, epitope mapping The Journal of biological chemistry High 1860863
1993 CD19 and TAPA-1 (CD81) interact through their extracellular domains; CD19 and CD21 interact through extracellular and transmembrane domains. The TAPA-1 component of the CD21/CD19/TAPA-1 complex is responsible for inducing homotypic cellular aggregation. Loss of CD21/TAPA-1 interaction removes aggregation but not PI3-kinase recruitment or calcium signaling. Chimeric molecule expression (HLA-A2 and CD4 domain substitutions), functional assays (Ca2+ flux, PI3-kinase co-precipitation, homotypic adhesion), B lymphoblastoid cell transfection The Journal of experimental medicine High 7690834
1993 The transmembrane domain of CD19 (not its cytoplasmic domain) is required for association with TAPA-1 (CD81) on the cell surface; deletion of 95% of the CD19 cytoplasmic tail does not affect CD19–TAPA-1 complex formation, but replacing the CD19 transmembrane+cytoplasmic domains with those of L-selectin abolishes the association. CD19 cytoplasmic deletion mutants, CD19/L-selectin chimera expression in Rex T cells and K562 cells, co-immunoprecipitation, Ca2+ flux assays Journal of immunology High 7690791
1993 TAPA-1 (CD81) is associated on the surface of B cells with HLA-DR; detected by co-immunoprecipitation with mild detergents, confirmed by 2D-SDS-PAGE, Western blot identification of TAPA-1 in anti-HLA-DR immunoprecipitates, and co-capping experiments. Co-immunoprecipitation (mild detergents), 2D-SDS-PAGE, Western blot, co-capping Journal of immunology Medium 8409388
1993 Anti-TAPA-1 antibody engagement induces rapid protein tyrosine phosphorylation in B cells, which is an early step upstream of the antiproliferative effect; this signal is dependent on intracellular thiol levels (glutathione) and is blocked by tyrosine kinase inhibitors. Protein tyrosine phosphorylation assays, tyrosine kinase inhibitors, thiol manipulation (2-ME, glutathione synthesis blockers) Journal of immunology Medium 7688390
1996 CD81 (TAPA-1) specifically associates with integrin α4β1 (VLA-4) on hemopoietic cell lines; the association is reciprocal by co-immunoprecipitation, is independent of the α4 cytoplasmic domain and divalent cations, but is abolished in two α4 adhesion-deficient point mutants (D346E and D408E). CD81 does not associate with α2β1, α5β1, or αLβ2 integrins. Reciprocal co-immunoprecipitation, confocal microscopy co-localization, adhesion-deficient α4 mutants Journal of immunology High 8757325
1997 CD81 and CD63 form specific complexes with phosphatidylinositol 4-kinase (PI4K type II, ~55 kDa) and with α3β1 integrin; these complexes are located in focal complexes at the cell periphery rather than focal adhesions, providing a signaling pathway distinct from conventional integrin–FAK signaling. Enzymatic PI4K assays, immunochemical assays, co-immunoprecipitation, immunofluorescence/confocal microscopy The Journal of biological chemistry High 9006891
1998 CD81/TAPA-1 localizes to endothelial cell–cell lateral junctions and regulates cell motility; anti-CD81 antibodies inhibit endothelial cell migration in wound-healing assays and reduce individual cell movement as measured by quantitative time-lapse video microscopy. Immunofluorescence microscopy (localization), wound-healing migration assay, time-lapse video microscopy, collagen invasion assay, biochemical co-immunoprecipitation The Journal of cell biology High 9566977
2000 FPRP (prostaglandin F2α receptor regulatory protein, 133 kDa), an Ig superfamily protein, is a major and highly stoichiometric (~100%) specific molecular partner of CD81 and CD9 at the cell surface; CD81–CD9–FPRP complexes are discrete in size (<4×10⁶ Da) and remain intact after cholesterol-rich microdomain disruption by methyl-β-cyclodextrin. CD81–FPRP complexes are distinct from CD81–α3β1 integrin complexes. Co-immunoprecipitation, immunodepletion, gel permeation chromatography, methyl-β-cyclodextrin treatment, mass spectrometry identification The Journal of biological chemistry High 11087758
2001 CD9P-1 (FPRP/KIAA1436) is identified as the major molecular partner of both CD9 and CD81 in cancer cell lines; CD9P-1 forms direct complexes with CD81 (and separately with CD9), with complex formation requiring the second half of CD9 (large extracellular loop and fourth transmembrane domain), as shown by chimeric CD9/CD82 molecules. Immunoaffinity purification, mass spectrometry, cross-linking, chimeric CD9/CD82 molecule expression, co-immunoprecipitation The Journal of biological chemistry High 11278880
2002 Hepatocyte CD81 is required for Plasmodium falciparum and P. yoelii sporozoite infectivity; P. yoelii sporozoites fail to infect CD81-deficient mouse hepatocytes in vivo and in vitro, and anti-CD81 antibodies inhibit hepatic development of both species. The requirement for CD81 is specifically linked to sporozoite entry by parasitophorous vacuole (PV) formation. CD81-knockout mice (in vivo and in vitro infection), antibody inhibition assays, infection quantification Nature medicine High 12483205
2003 CD9 and CD81 function to prevent fusion of mononuclear phagocytes; CD9/CD81-null mice spontaneously develop multinucleated giant cells in the lung and show enhanced osteoclastogenesis. Under fusogenic conditions, complex formation of CD9 and CD81 with integrins is down-regulated, enabling fusion. CD9/CD81 double-knockout mice, in vitro and in vivo fusion assays (alveolar macrophages, bone marrow cells), anti-CD9/CD81 antibody treatment, confocal microscopy The Journal of cell biology High 12796480
2003 CD81 regulates CD19 expression in B cells in a post-endoplasmic reticulum compartment; cd81−/− B cells express lower levels of the higher-Mr (endo-H resistant, post-ER) glycoform of CD19 but normal levels of the endo-H sensitive (ER-localized) glycoform. Human CD81 expression in cd81−/− B cells restores surface CD19 to normal levels. This dependency is specific to CD81 (cd9−/− B cells have normal CD19). CD81-knockout mouse B cells, retroviral CD81 transduction, endoglycosidase H sensitivity assay, quantitative mRNA analysis, flow cytometry Journal of immunology High 14530327
2004 CD81 is required for HCV glycoprotein-mediated viral entry; siRNA silencing of CD81 in Huh-7.5 cells inhibits HIV-HCV pseudotype infection, and expression of CD81 in previously resistant liver cell lines (HepG2, HH29) confers permissivity. The large extracellular loop (LEL) of CD81 (determined by chimeric CD9/CD81 molecules) is the determinant for viral entry. Retroviral pseudotyping (HIV-HCV pseudotypes), siRNA knockdown, CD81 expression in CD81-negative cells, chimeric CD9/CD81 molecules, neutralizing antibody inhibition Journal of virology High 14722300
2004 Coligation of the BCR with the CD19/CD21/CD81 coreceptor complex induces selective, rapid, and reversible palmitoylation of CD81; this palmitoylation is necessary for the raft-stabilizing function of the coreceptor complex and for amplified BCR signaling. Metabolic palmitoylation labeling, lipid raft fractionation, BCR co-ligation assays, palmitoylation inhibition The Journal of biological chemistry Medium 15161911
2004 CD81 associates with the ε isoform of 14-3-3 (an intracellular serine/threonine-binding signaling protein); this association is regulated by the palmitoylation state of CD81's cytoplasmic tails. Palmitoylation occurs on N- and C-terminal tails and the intracellular loop between TM2 and TM3. An unpalmitoylatable CD81 mutant (all 5 intracellular cysteines mutated) shows constitutive 14-3-3 association. Oxidative conditions inhibit CD81 palmitoylation and promote 14-3-3 binding. Co-immunoprecipitation, CD81 cysteine mutagenesis (palmitoylation-site mapping), palmitoylation assays, oxidative stress experiments The Journal of biological chemistry Medium 14966136
2005 The large extracellular loop (LEL) residues Y527 and W529 in HCV E2 (region 2) are critical for binding to CD81; region 1 (aa 474–492) mutations reduce infectivity without disrupting CD81 binding, indicating region 1 does not mediate CD81 binding. Region 3 (aa 612–619) residues are also important for E2 binding to CD81. Alanine-substitution mutagenesis of HCV E2, lentiviral HCV pseudoparticles (HCVpp), CD81-GST binding assays, infectivity assays Biochemical and biophysical research communications Medium 15670777
2006 CD81 LEL from human (and weakly from African green monkey) supports HCV E2 binding and inhibits HCVpp infection, while mouse or rat CD81 LEL fails to bind sE2 or inhibit infection. However, full-length CD81 from all species supports HCVpp infection to varying degrees. The recombinant human CD81 LEL inhibits HCVpp only when present during virus-cell incubation, consistent with a post-attachment role for CD81. Recombinant LEL protein expression, HCV E2 binding assays, HCVpp infection assays, site-directed mutagenesis (I182F, N184Y, F186S) in full-length CD81 Journal of virology Medium 16943299
2006 CD81 loss-of-function in the mesolimbic dopaminergic pathway suppresses cocaine-induced locomotor behavior; lentiviral CD81 overexpression in nucleus accumbens or VTA increases locomotor activity after chronic cocaine, while CD81 shRNA silencing in vivo decreases basal and cocaine-induced locomotion. Lentiviral in vivo gene delivery (overexpression and shRNA knockdown), stereotaxic injection, locomotor activity measurement, qRT-PCR, immunocytochemistry Journal of neurochemistry Medium 15715673
2008 CD81 associates with claudin-1 (CLDN1) in HCV coreceptor complexes; FRET between GFP/RFP-tagged CD81 and CLDN1 occurs in permissive and non-permissive cells and in human liver tissue. HCV infection and anti-CD81 mAb treatment modulate CD81-CD81 (homotypic) and CD81-CLDN1 (heterotypic) associations at specific cellular locations, indicating distinct roles in entry. FRET (tagged CD81 and CLDN1), confocal co-localization, antibody treatment modulation assays, human liver tissue staining Journal of virology Medium 18337570
2008 Interaction with the CD81 large extracellular domain (LEL) by HCV functions at a post-attachment step; anti-CD81 antibodies block infection at late times after virus internalization, consistent with an intracellular role for CD81 in HCV infection. Anti-CD81 antibody time-of-addition assays, siRNA knockdown, HCV pseudoparticle and cell culture virus infection assays Gastroenterology Low 18466772
2008 CD81 interacts with PI4KII to suppress HCC cell motility; this is mediated by formation of CD81-enriched vesicles that sequester actinin-4 and remodel the actin cytoskeleton. Both loss- and gain-of-function approaches confirmed CD81's inhibitory role in HCC cell motility. siRNA knockdown, CD81 overexpression, confocal microscopy, vesicle isolation, actinin-4 co-localization, migration assays Gastroenterology Medium 18466772
2009 CD81 engagement on B-lymphocytes induces tyrosine phosphorylation of ezrin (an actin-binding ERM family protein) and its redistribution with F-actin; Syk kinase is activated downstream of CD81 and is required for ezrin phosphorylation. After CD81 engagement, CD81 co-localizes with ezrin and F-actin, and this association is disrupted by Syk inhibition. Mass spectrometry of CD81-engagement-induced phosphoproteins, co-immunoprecipitation, immunofluorescence co-localization, Syk inhibitor treatment Journal of cell science Medium 19654214
2009 CD81 stimulation of NK cells induces phosphorylation of ezrin/radixin/moesin proteins and NK cell polarization, facilitating NK cell migration toward chemokines/cytokines; CD81 also promotes NK cell adhesion to extracellular matrix components. Anti-CD81 antibody stimulation, ERM phosphorylation assays, cell polarization assay, migration assays, adhesion assays European journal of immunology Medium 19830727
2009 CD81-deficient B cells show enhanced BCR signaling: cd81−/− B cells exhibit higher intracellular Ca2+ flux, increased Syk and PLCγ2 phosphorylation upon BCR stimulation, and enhanced NF-κB activation, proliferation, and antibody secretion in response to TLR4 stimulation compared with WT. This hyperactive phenotype is cell-intrinsic (confirmed by bone marrow transplant into Rag1−/− mice). Therefore, CD81 plays a negative regulatory role in B cell activation. Ca2+ flux assay, phosphorylation assays (Syk, PLCγ2), NF-κB activation assay, proliferation assay, bone marrow transplantation into Rag1−/− mice, T-independent antigen immunization International immunology High 19737782
2009 CD9P-1 (EWI-F) acts as a negative regulator of P. yoelii sporozoite hepatocyte infection by interacting directly with CD81 via their transmembrane regions; CD9P-1 silencing increases and CD9P-1 overexpression decreases host cell susceptibility to sporozoite infection. A CD9P-1 chimera that cannot associate with CD81 does not affect infection. EWI-2 knockdown has no effect. siRNA knockdown of CD9P-1 and EWI-2, CD9P-1 overexpression, chimeric CD81/CD9P-1 molecules, Plasmodium yoelii infection assays The Journal of biological chemistry Medium 19762465
2010 Homozygous CD81 mutation in a patient causes complete lack of CD81 expression and consequent absence of CD19 on B cell surface, leading to antibody deficiency. Retroviral transduction of CD81 into patient's EBV-transformed B cells rescues CD19 membrane expression. CD81-deficient patient B cells show impaired activation upon BCR stimulation, demonstrating the non-redundant role of CD81 in CD19 complex formation and B cell function in humans. Patient genetic analysis (homozygous CD81 mutation), flow cytometry (CD19 surface expression), retroviral transduction rescue, glycosylation experiments, BCR stimulation assays The Journal of clinical investigation High 20237408
2010 MARCH-VIII and MARCH-IV (transmembrane ubiquitin ligases) sequester CD81 in endo-lysosomal vesicles, reducing its surface expression; MARCH-IV knockdown increases endogenous surface CD81 levels, indicating constitutive involvement of MARCH proteins in CD81 turnover. SILAC-based differential proteomics, MARCH overexpression and siRNA knockdown, flow cytometry (surface expression), immunofluorescence PloS one Medium 21151997
2012 CD81 undergoes internalization via a clathrin- and dynamin-dependent process that is independent of CD81's cytoplasmic domain, implicating associated partner proteins in regulating CD81 trafficking. CD81 and claudin-1 are co-endocytosed and fuse with Rab5-positive endosomes. HCV particles and receptor-specific antibodies increase CD81 and claudin-1 endocytosis. Live cell imaging, fluorescence microscopy (Rab5-endosome fusion), dominant-negative dynamin and clathrin constructs, CD81 cytoplasmic domain deletion mutant, HCV infection assays Journal of virology Medium 22318146
2012 In silico-guided mutagenesis identifies a molecular interface between CD81 (residues T149, E152, T153) and the first extracellular loop of claudin-1 (aa 62–66) as critical for CD81–CLDN1 complex formation and HCV infection; FRET studies confirm this interface, and these CD81 mutations have minimal impact on protein conformation or HCV glycoprotein binding. Bioinformatic structural modelling, site-directed mutagenesis of CD81, FRET imaging, HCV infection assays Cellular microbiology Medium 22897233
2012 EWI-2wint promotes CD81 clustering and confinement in CD81-enriched membrane areas, reducing CD81 diffusion and its co-localization with claudin-1, thereby blocking HCV entry. Single-molecule microscopy shows reduced global CD81 diffusion rate and increased proportion of confined molecules in EWI-2wint-expressing cells. Single-molecule microscopy (single-particle tracking), biochemical co-immunoprecipitation, HCV infection assays, CD81-CLDN1 co-localization imaging Cellular microbiology Medium 23351194
2013 CD81 controls T cell immune synapse (IS) organization and sustained TCR signaling; FRAP, phasor FLIM-FRET, and TIRFM show that CD81 interacts dynamically with ICAM-1 and CD3 during T cell–APC conjugation. CD81 is required for proper phosphorylation of CD3ζ, ZAP-70, LAT, and ERK; CD69 surface expression; and IL-2 secretion. FRAP, phasor FLIM-FRET, TIRFM, phosphorylation assays (CD3ζ, ZAP-70, LAT, ERK), CD69 and IL-2 functional readouts, CD81 knockdown Molecular and cellular biology High 23858057
2013 Dual siRNA silencing of CD9 and CD81 (not either alone) impairs α3β1-dependent directed motility and front-rear cell morphology in breast carcinoma cells; CD9/CD81 (but not CD151) is required to promote α3β1 association with PKCα, and a PKC inhibitor mimics the CD9/CD81-silenced motility defect. siRNA double knockdown, α3β1-dependent migration assays, co-immunoprecipitation (α3β1–PKCα), PKC inhibitor treatment, cell spreading assays PloS one Medium 23613949
2015 IFI6 (interferon-α inducible protein 6) impairs CD81 co-localization with claudin-1 and inhibits EGFR activation induced by CD81 cross-linking or HCV infection, thereby blocking HCV entry. EGFR activation specifically by CD81 antibody (but not by EGF) is reduced in IFI6-expressing cells, identifying EGFR as a mediator of CD81-CLDN1 interaction. IFI6 overexpression, co-localization imaging, EGFR phosphorylation assays, CD81 cross-linking, HCV infection assays Scientific reports Medium 25757571
2016 The EC2 domains of CD81, CD9, and CD151 bind to the classical RGD-binding site (ligand-binding site) of integrin αvβ3; this binding is suppressed by cRGDfV and antibody 7E3 (mapped to β3 ligand-binding site). Docking simulation and Lys116/Lys144/Lys148 mutagenesis of CD81 EC2 identify helices A and B as the integrin-binding interface. Cell adhesion assays, blocking with cRGDfV and 7E3 antibody, docking simulation, site-directed mutagenesis of CD81 EC2 (K116, K144, K148 substitutions) The Biochemical journal Medium 27993971
2017 CD81 directly interacts with SAMHD1 (dNTP phosphohydrolase), preventing its endosomal accumulation and promoting its proteasome-dependent degradation; CD81 depletion increases SAMHD1 expression, decreasing cellular dNTP availability and HIV-1 reverse transcription. CD81 overexpression (but not a C-terminal deletion mutant) increases dNTPs and HIV-1 reverse transcription. Co-immunoprecipitation (CD81–SAMHD1), CD81 knockdown/overexpression, SAMHD1 protein expression/localization analysis, dNTP level measurement, HIV-1 reverse transcription assay, proteasome inhibitor treatment, CD81 C-terminal deletion mutant Nature microbiology High 28871089
2018 CD81 forms a complex with calpain-5 (CAPN5) and the ubiquitin ligase CBLB in primary human liver and hepatoma cells; CAPN5 and CBLB support HCV entry at a post-binding, pre-replication step for all tested HCV genotypes but not for VSV or coronavirus. Plasmodium sporozoites rely on a distinct set of CD81 interaction partners for liver cell entry. Quantitative proteomics (CD81 interactome mapping in primary human liver cells), CAPN5/CBLB knockout, HCV entry assays (multiple genotypes), Plasmodium infection assays PLoS pathogens High 30024968
2020 CD81 forms a complex with αV/β1 and αV/β5 integrins and mediates activation of integrin-FAK signaling in adipocyte progenitor cells in response to irisin; CD81 is required for de novo beige fat biogenesis following cold exposure. CD81 loss causes diet-induced obesity, insulin resistance, and adipose tissue inflammation. Single-cell RNA-seq, co-immunoprecipitation (CD81–integrin complex), FAK signaling assays, irisin stimulation, CD81-knockout mice (cold exposure, diet-induced obesity, metabolic phenotyping) Cell High 32615086
2020 Structure-led mutagenesis of CD81's intramembrane cholesterol-binding pocket reveals that cholesterol binding regulates an allosteric conformational switch in CD81's large extracellular domain; mutations forcing the 'open' (cholesterol-unbound) conformation reduce HCV receptor activity, while mutations forcing the 'closed' (cholesterol-bound) conformation enhance it. CD81 interactome analysis suggests that conformational switching modulates CD81–partner protein network assembly. Site-directed mutagenesis of cholesterol-binding pocket, cholesterol association assays, molecular dynamics simulations, HCV infection assays, CD81 interactome analysis The Journal of biological chemistry Medium 32900848
2020 CD81 uses its ectodomain to traffic CD19 to the cell surface; mutations of CD81 at the CD19-binding interface (identified by the anti-CD81 antibody 5A6 epitope) suppress CD19 export activity. The 5A6 antibody recognizes a conformational epitope on CD81 that is masked when CD81 is bound to CD19, indicating dynamic regulation of the CD81–CD19 interaction upon B cell activation. CD81 mutagenesis at CD19-binding interface, CD19 surface trafficking assays, epitope mapping (5A6 antibody), flow cytometry eLife Medium 32338599
2021 Cryo-EM structure of CD19 bound to CD81 at 3.8 Å reveals that CD81 opens its ectodomain to expose a hydrophobic CD19-binding surface upon CD19 engagement, and reorganizes its transmembrane helices to occlude a cholesterol-binding pocket present in the apoprotein. The contact interface between ectodomains drives complex formation. Cryo-electron microscopy (cryo-EM) at 3.8 Å with bound therapeutic Fab Science High 33446559
2021 CD81 promotes nuclear translocation of Rad51 after radiation, supporting homologous recombination repair (HRR) in glioblastoma cells; CD81 knockdown reduces nuclear Rad51, enhances radiation-induced γ-H2AX, and sensitizes cells to radiation. The Rad51 inhibitor B02 abolishes the sensitization effect of CD81 knockdown, placing Rad51 as an effector of CD81 in radioresistance. Dual immunofluorescence shows nuclear membrane CD81 co-localization with Rad51 after irradiation. siRNA/shRNA CD81 knockdown, in vitro and in vivo xenograft irradiation, γ-H2AX assays, nuclear Rad51 immunofluorescence, B02 Rad51 inhibitor epistasis Cancers Medium 33919192
2022 CD81 interacts with CD44 through their extracellular regions to promote tumor cell cluster formation and lung metastasis of triple-negative breast cancer; protein structure modeling and interface prediction-guided mutagenesis demonstrate that this interaction mediates stemness and metastasis. CD81 or CD44 deficiency alters endocytosis-related pathways and impairs EV secretion quality. Machine learning-assisted protein structure modeling, interface prediction-guided mutagenesis, in vivo metastasis models (human and mouse TNBC), global and phosphoproteomic analyses, EV characterization eLife Medium 36193887
2013 CD81 affects influenza virus infection at two distinct stages: (1) approximately half of fused influenza particles undergo fusion within CD81-positive endosomes, and CD81 depletion causes a substantial defect in viral fusion; (2) during virus assembly, CD81 is recruited to budding sites on the plasma membrane and its knockdown causes elongated budding virions that remain attached to the plasma membrane, reducing progeny virus production. siRNA knockdown, live cell fluorescence imaging (single-particle tracking of influenza), confocal microscopy (CD81-positive endosome co-localization), electron microscopy of budding virions PLoS pathogens Medium 24130495
2001 CD81 is required for neuron-induced astrocyte cell-cycle exit; CD81 is expressed on the astrocyte surface and its level is modulated by neuronal contact. A specific extracellular domain of CD81 (recognized by antibody Eat1) is required for astrocyte cell-cycle withdrawal in response to neurons. CD81-null astrocytes fail to arrest proliferation in response to neuronal signals. CD81-knockout mice, astrocyte-neuron co-culture, anti-CD81 antibody perturbation (three distinct epitope antibodies), cell cycle assays Molecular and cellular neurosciences Medium 11273649
2002 CD81 is released from activated lymphocytes on microparticles, rapidly reducing surface CD81 levels; CD81-positive microparticles transfer CD81 to CD81-negative acceptor cells (U937), and this intercellular transfer is enhanced by T cell activation. This mechanism regulates surface CD81 expression independently of transcription. Quantitative flow cytometry, microparticle isolation and characterization, coculture transfer experiments, CD81 mRNA quantification Journal of immunology Medium 12421929

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1998 CD81 (TAPA-1): a molecule involved in signal transduction and cell adhesion in the immune system. Annual review of immunology 419 9597125
1995 The CD19/CR2/TAPA-1 complex of B lymphocytes: linking natural to acquired immunity. Annual review of immunology 396 7542009
1990 TAPA-1, the target of an antiproliferative antibody, defines a new family of transmembrane proteins. Molecular and cellular biology 357 1695320
2004 CD81 is required for hepatitis C virus glycoprotein-mediated viral infection. Journal of virology 293 14722300
2010 CD81 gene defect in humans disrupts CD19 complex formation and leads to antibody deficiency. The Journal of clinical investigation 285 20237408
2002 Hepatocyte CD81 is required for Plasmodium falciparum and Plasmodium yoelii sporozoite infectivity. Nature medicine 260 12483205
2020 CD81 Controls Beige Fat Progenitor Cell Growth and Energy Balance via FAK Signaling. Cell 235 32615086
1998 Regulation of endothelial cell motility by complexes of tetraspan molecules CD81/TAPA-1 and CD151/PETA-3 with alpha3 beta1 integrin localized at endothelial lateral junctions. The Journal of cell biology 227 9566977
1997 A novel link between integrins, transmembrane-4 superfamily proteins (CD63 and CD81), and phosphatidylinositol 4-kinase. The Journal of biological chemistry 222 9006891
1996 Transmembrane-4 superfamily proteins CD81 (TAPA-1), CD82, CD63, and CD53 specifically associated with integrin alpha 4 beta 1 (CD49d/CD29). Journal of immunology (Baltimore, Md. : 1950) 200 8757325
1993 Functional dissection of the CD21/CD19/TAPA-1/Leu-13 complex of B lymphocytes. The Journal of experimental medicine 196 7690834
2001 The major CD9 and CD81 molecular partner. Identification and characterization of the complexes. The Journal of biological chemistry 193 11278880
2003 Tetraspanins CD9 and CD81 function to prevent the fusion of mononuclear phagocytes. The Journal of cell biology 163 12796480
2008 CD81 and claudin 1 coreceptor association: role in hepatitis C virus entry. Journal of virology 158 18337570
2009 CD81 is dispensable for hepatitis C virus cell-to-cell transmission in hepatoma cells. The Journal of general virology 150 19088272
1990 TAPA-1, the target of an antiproliferative antibody, is associated on the cell surface with the Leu-13 antigen. Journal of immunology (Baltimore, Md. : 1950) 141 2398277
2009 PCSK9 impedes hepatitis C virus infection in vitro and modulates liver CD81 expression. Hepatology (Baltimore, Md.) 132 19489072
2006 Tetraspanins CD9 and CD81 modulate HIV-1-induced membrane fusion. Journal of immunology (Baltimore, Md. : 1950) 131 17015697
2006 Diverse CD81 proteins support hepatitis C virus infection. Journal of virology 126 16943299
2000 FPRP, a major, highly stoichiometric, highly specific CD81- and CD9-associated protein. The Journal of biological chemistry 118 11087758
2023 Differential proteomics argues against a general role for CD9, CD81 or CD63 in the sorting of proteins into extracellular vesicles. Journal of extracellular vesicles 105 37525398
2003 The tetraspanin CD81 regulates the expression of CD19 during B cell development in a postendoplasmic reticulum compartment. Journal of immunology (Baltimore, Md. : 1950) 105 14530327
2012 Hepatitis C virus induces CD81 and claudin-1 endocytosis. Journal of virology 103 22318146
1993 The CD19 signal transduction complex of B lymphocytes. Deletion of the CD19 cytoplasmic domain alters signal transduction but not complex formation with TAPA-1 and Leu 13. Journal of immunology (Baltimore, Md. : 1950) 101 7690791
2004 B cell signaling is regulated by induced palmitoylation of CD81. The Journal of biological chemistry 91 15161911
2013 Dual function of CD81 in influenza virus uncoating and budding. PLoS pathogens 88 24130495
2014 CD81 and hepatitis C virus (HCV) infection. Viruses 85 24509809
2014 Function of the tetraspanin molecule CD81 in B and T cells. Immunologic research 84 24522698
2006 Expression of human CD81 differently affects host cell susceptibility to malaria sporozoites depending on the Plasmodium species. Cellular microbiology 78 16819966
1993 The CD19-CR2-TAPA-1 complex, CD45 and signaling by the antigen receptor of B lymphocytes. Current opinion in immunology 75 7688513
1993 The TAPA-1 molecule is associated on the surface of B cells with HLA-DR molecules. Journal of immunology (Baltimore, Md. : 1950) 73 8409388
1991 Structure and membrane topology of TAPA-1. The Journal of biological chemistry 71 1860863
2002 Increased brain size and glial cell number in CD81-null mice. The Journal of comparative neurology 70 12357429
2010 Membrane-Associated RING-CH proteins associate with Bap31 and target CD81 and CD44 to lysosomes. PloS one 67 21151997
2008 Tetraspanin CD81-regulated cell motility plays a critical role in intrahepatic metastasis of hepatocellular carcinoma. Gastroenterology 66 18466772
1993 Anti-TAPA-1 antibodies induce protein tyrosine phosphorylation that is prevented by increasing intracellular thiol levels. Journal of immunology (Baltimore, Md. : 1950) 65 7688390
2002 Release and intercellular transfer of cell surface CD81 via microparticles. Journal of immunology (Baltimore, Md. : 1950) 63 12421929
2010 Tupaia CD81, SR-BI, claudin-1, and occludin support hepatitis C virus infection. Journal of virology 62 21177818
2013 CD81 controls sustained T cell activation signaling and defines the maturation stages of cognate immunological synapses. Molecular and cellular biology 60 23858057
2015 Interferon-α inducible protein 6 impairs EGFR activation by CD81 and inhibits hepatitis C virus infection. Scientific reports 59 25757571
2021 Cryo-EM structure of the B cell co-receptor CD19 bound to the tetraspanin CD81. Science (New York, N.Y.) 58 33446559
2012 CD81 and CD9 work independently as extracellular components upon fusion of sperm and oocyte. Biology open 57 23213457
2020 A dynamic interaction between CD19 and the tetraspanin CD81 controls B cell co-receptor trafficking. eLife 56 32338599
1991 Genomic organization and chromosomal localization of the TAPA-1 gene. Journal of immunology (Baltimore, Md. : 1950) 56 1650385
2004 CD81 associates with 14-3-3 in a redox-regulated palmitoylation-dependent manner. The Journal of biological chemistry 55 14966136
2017 CD81 as a tumor target. Biochemical Society transactions 54 28408492
2000 CD81 and CD28 costimulate T cells through distinct pathways. Journal of immunology (Baltimore, Md. : 1950) 54 10925271
2008 Dissecting the role of putative CD81 binding regions of E2 in mediating HCV entry: putative CD81 binding region 1 is not involved in CD81 binding. Virology journal 53 18355410
2007 The roles of CD81 and glycosaminoglycans in the adsorption and uptake of infectious HCV particles. Journal of medical virology 53 17457918
2014 HIV-1 entry and trans-infection of astrocytes involves CD81 vesicles. PloS one 52 24587404
2012 MGMT, GATA6, CD81, DR4, and CASP8 gene promoter methylation in glioblastoma. BMC cancer 52 22672670
1997 A 1-Mb physical map and PAC contig of the imprinted domain in 11p15.5 that contains TAPA1 and the BWSCR1/WT2 region. Genomics 51 9268640
2021 Targeting the tetraspanin CD81 reduces cancer invasion and metastasis. Proceedings of the National Academy of Sciences of the United States of America 50 34099563
2005 In vivo gene silencing of CD81 by lentiviral expression of small interference RNAs suppresses cocaine-induced behaviour. Journal of neurochemistry 50 15715673
2001 Cocaine-induced expression of the tetraspanin CD81 and its relation to hypothalamic function. Molecular and cellular neurosciences 48 11178868
2021 CD81 marks immature and dedifferentiated pancreatic β-cells. Molecular metabolism 46 33582383
2018 Hepatitis C virus enters liver cells using the CD81 receptor complex proteins calpain-5 and CBLB. PLoS pathogens 45 30024968
2009 Engagement of CD81 induces ezrin tyrosine phosphorylation and its cellular redistribution with filamentous actin. Journal of cell science 44 19654214
2001 CD81 regulates neuron-induced astrocyte cell-cycle exit. Molecular and cellular neurosciences 44 11273649
2018 Double deletion of tetraspanins CD9 and CD81 in mice leads to a syndrome resembling accelerated aging. Scientific reports 41 29572511
2020 KLF4-mediated upregulation of CD9 and CD81 suppresses hepatocellular carcinoma development via JNK signaling. Cell death & disease 40 32350244
2013 The CD9/CD81 tetraspanin complex and tetraspanin CD151 regulate α3β1 integrin-dependent tumor cell behaviors by overlapping but distinct mechanisms. PloS one 40 23613949
2019 CD81 is a novel immunotherapeutic target for B cell lymphoma. The Journal of experimental medicine 37 31123084
2012 CD81 is a candidate tumor suppressor gene in human gastric cancer. Cellular oncology (Dordrecht, Netherlands) 36 23264205
2011 Hepatitis C virus entry and the tetraspanin CD81. Biochemical Society transactions 35 21428934
2005 Determinants of CD81 dimerization and interaction with hepatitis C virus glycoprotein E2. Biochemical and biophysical research communications 35 15670777
2009 CD81 protein is expressed at high levels in normal germinal center B cells and in subtypes of human lymphomas. Human pathology 34 20004001
2019 The tetraspanin CD81 mediates the growth and metastases of human osteosarcoma. Cellular oncology (Dordrecht, Netherlands) 33 31494861
2017 Up-regulation of CD81 inhibits cytotrophoblast invasion and mediates maternal endothelial cell dysfunction in preeclampsia. Proceedings of the National Academy of Sciences of the United States of America 32 28167787
2017 CD81 association with SAMHD1 enhances HIV-1 reverse transcription by increasing dNTP levels. Nature microbiology 32 28871089
2014 CD81-receptor associations--impact for hepatitis C virus entry and antiviral therapies. Viruses 32 24553110
2013 EWI-2wint promotes CD81 clustering that abrogates Hepatitis C Virus entry. Cellular microbiology 32 23351194
2012 Complementary costimulation of human T-cell subpopulations by cluster of differentiation 28 (CD28) and CD81. Proceedings of the National Academy of Sciences of the United States of America 32 22307619
2022 Machine learning-assisted elucidation of CD81-CD44 interactions in promoting cancer stemness and extracellular vesicle integrity. eLife 31 36193887
2001 Anti-CD81 activates LFA-1 on T cells and promotes T cell-B cell collaboration. European journal of immunology 31 11241287
2000 Up-regulation of CD81 (target of the antiproliferative antibody; TAPA) by reactive microglia and astrocytes after spinal cord injury in the rat. The Journal of comparative neurology 31 11064366
2016 Hepatitis C virus infection propagates through interactions between Syndecan-1 and CD81 and impacts the hepatocyte glycocalyx. Cellular microbiology 30 27930836
2012 In silico directed mutagenesis identifies the CD81/claudin-1 hepatitis C virus receptor interface. Cellular microbiology 30 22897233
2012 Hepatoma polarization limits CD81 and hepatitis C virus dynamics. Cellular microbiology 30 23126643
2022 Natural flavonoids effectively block the CD81 receptor of hepatocytes and inhibit HCV infection: a computational drug development approach. Molecular diversity 29 35821161
2023 Targeting of Tetraspanin CD81 with Monoclonal Antibodies and Small Molecules to Combat Cancers and Viral Diseases. Cancers 28 37046846
2018 Conformational Flexibility in the CD81-Binding Site of the Hepatitis C Virus Glycoprotein E2. Frontiers in immunology 28 29967619
2017 Mice Expressing Minimally Humanized CD81 and Occludin Genes Support Hepatitis C Virus Uptake In Vivo. Journal of virology 28 27928007
2016 The CD9, CD81, and CD151 EC2 domains bind to the classical RGD-binding site of integrin αvβ3. The Biochemical journal 28 27993971
2013 Tetraspanins CD81 and CD82 facilitate α4β1-mediated adhesion of human erythroblasts to vascular cell adhesion molecule-1. PloS one 28 23704882
2023 Parallel SPR and QCM-D Quantitative Analysis of CD9, CD63, and CD81 Tetraspanins: A Simple and Sensitive Way to Determine the Concentration of Extracellular Vesicles Isolated from Human Lung Cancer Cells. Analytical chemistry 27 37307147
2010 The tetraspanins CD9 and CD81 regulate CD9P1-induced effects on cell migration. PloS one 27 20574531
2000 Differential expression of murine CD81 highlighted by new anti-mouse CD81 monoclonal antibodies. Hybridoma 27 10768837
2021 The Fatty Acid and Protein Profiles of Circulating CD81-Positive Small Extracellular Vesicles Are Associated with Disease Stage in Melanoma Patients. Cancers 25 34439311
2019 Differential Expression of CD43, CD81, and CD200 in Classic Versus Variant Hairy Cell Leukemia. Cytometry. Part B, Clinical cytometry 24 31077558
2020 Cholesterol sensing by CD81 is important for hepatitis C virus entry. The Journal of biological chemistry 23 32900848
2016 Characterization of tetraspanin protein CD81 in mouse spermatozoa and bovine gametes. Reproduction (Cambridge, England) 22 27679865
2009 Enhanced B cell activation in the absence of CD81. International immunology 22 19737782
2017 The importance of CD39, CD43, CD81, and CD95 expression for differentiating B cell lymphoma by flow cytometry. Cytometry. Part B, Clinical cytometry 21 28509416
2009 Regulation of NK cell trafficking by CD81. European journal of immunology 21 19830727
2021 CD81 Enhances Radioresistance of Glioblastoma by Promoting Nuclear Translocation of Rad51. Cancers 20 33919192
2020 CD81 knockout promotes chemosensitivity and disrupts in vivo homing and engraftment in acute lymphoblastic leukemia. Blood advances 20 32926125
2009 The Ig domain protein CD9P-1 down-regulates CD81 ability to support Plasmodium yoelii infection. The Journal of biological chemistry 20 19762465
2008 High-level expression, single-step immunoaffinity purification and characterization of human tetraspanin membrane protein CD81. PloS one 20 18523555
1996 Ligation of TAPA-1 (CD81) or major histocompatibility complex class II in co-cultures of human B and T lymphocytes enhances interleukin-4 synthesis by antigen-specific CD4+ T cells. European journal of immunology 19 8766544

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