| 2008 |
XTP3-B/ERLEC1 is an ER-resident glycoprotein that binds to ERAD substrates and, through the SEL1L adaptor, to the ER-membrane-embedded ubiquitin ligase Hrd1. Its MRH domain is required for interaction with SEL1L but not with substrate. XTP3-B and OS-9 form components of distinct, partially redundant quality control surveillance pathways coordinating protein folding with membrane dislocation and ubiquitin conjugation. |
Co-immunoprecipitation, siRNA knockdown, pulse-chase degradation assays |
Nature cell biology |
High |
18264092
|
| 2008 |
The long isoform of human XTP3-B (hXTP3-B) associates with the HRD1-SEL1L membrane-anchored ubiquitin ligase complex and BiP, forming a ~27S ER quality control scaffold complex. The short isoform is excluded from scaffold formation. hOS-9 is also incorporated into this large complex. hXTP3-B long isoform inhibits ERAD of NHK (null Hong Kong alpha1-antitrypsin variant), including a non-glycosylated version (NHK-QQQ), while the short isoform has almost no effect. |
Immunoprecipitation, sucrose density gradient centrifugation fractionation, siRNA knockdown, pulse-chase degradation assays |
The Journal of biological chemistry |
High |
18502753
|
| 2009 |
XTP3-B binds to the ERAD substrate alpha1-antitrypsin variant NHK (but not wild-type AT) specifically via its C-terminal MRH domain in a glycan-dependent manner. Mutation of Arg428 or Tyr457 in the C-terminal MRH domain abolishes glycan binding. The N-terminal MRH domain is dispensable for substrate binding. |
Recombinant Fc-fusion protein binding assays to Lec1 cells, EndoH treatment, competitive inhibition with mannose oligosaccharides, alanine mutagenesis, co-immunoprecipitation |
Glycobiology |
High |
19917667
|
| 2010 |
Disposal of soluble ERAD-LS substrates (nontransmembrane polypeptides with luminal lesions) is strictly dependent on XTP3-B (and OS-9) acting as interchangeable ERAD lectins along with HRD1 and SEL1L. These ERAD factors become dispensable when the same polypeptides are membrane-tethered (ERAD-LM substrates), revealing a mammalian-specific distinction from yeast. |
siRNA knockdown, pulse-chase degradation assays, genetic epistasis with defined substrate variants |
The Journal of cell biology |
High |
20100910
|
| 2010 |
Mannose trimming is required for substrate association with XTP3-B and with E3 ubiquitin ligases HRD1 and SCF(Fbs2). Inhibition of mannose trimming (kifunensine or ERManI knockdown) prevents substrate colocalization with HRD1 and Fbs2 at the ERQC but not with EDEM1. Substrate association with XTP3-B remained dependent on mannose trimming even upon SEL1L knockdown, suggesting XTP3-B recognizes mannose-trimmed glycans for late ERAD steps. |
Co-immunoprecipitation, mannosidase inhibitor (kifunensine) treatment, siRNA knockdown of ERManI and SEL1L, confocal colocalization |
The Journal of biological chemistry |
Medium |
21062743
|
| 2012 |
XTP3-B interacts with unassembled core-glycosylated CD147 (an endogenous ERAD substrate), and this interaction is inhibited by mutations to conserved residues in the XTP3-B lectin domain. XTP3-B participates along with OS-9 in the OS-9/SEL1L/Hrd1 ERAD pathway for an endogenous constitutive substrate. |
Mass spectrometry identification, Co-immunoprecipitation, lectin domain mutagenesis, siRNA depletion, proteasome inhibitor assays |
Molecular biology of the cell |
Medium |
23097496
|
| 2013 |
The C-terminal MRH domain of XTP3-B specifically recognizes Man9GlcNAc2 (M9) glycans in vitro and on the ERAD substrate NHK in vivo. Endogenous XTP3-B is a component of the HRD1-SEL1L complex via direct interaction with SEL1L. Lectin activity is required for NHK binding but not for SEL1L association. Unlike OS-9, XTP3-B inhibits ERAD of NHK bearing M9 oligosaccharides, acting as a negative regulator of ERAD and protecting newly synthesized immature polypeptides from premature degradation. |
Frontal affinity chromatography (FAC), co-immunoprecipitation, siRNA knockdown, pulse-chase degradation assays, lectin-domain mutagenesis |
The FEBS journal |
High |
23356641
|
| 2012 |
Nonglycosylated BiP substrates (NS-1κ light chain and truncated Igγ heavy chain) interact with XTP3-B and OS-9, and require EDEM1 for degradation, revealing that XTP3-B can engage non-glycosylated ERAD substrates through protein-protein interactions, sharing the ERAD pathway with glycoproteins. |
Co-immunoprecipitation, siRNA knockdown, pulse-chase degradation assays |
The Journal of biological chemistry |
Medium |
23233672
|
| 2006 |
Erlectin (XTP3-B/ERLEC1) is an ER luminal resident protein with two MRH domains. It interacts with the Wnt co-receptor Kremen2 (Krm2) via one MRH domain in a glycan-dependent manner (interaction abolished by Krm2 deglycosylation). Erlectin overexpression inhibits transport of Krm2 to the cell surface. Morpholino knockdown in Xenopus causes head and axial defects, placing Erlectin in ER glycoprotein trafficking regulation. |
Proteomic interaction screen, co-immunoprecipitation, deglycosylation assay, cell surface transport assay, Xenopus morpholino knockdown |
The Journal of biological chemistry |
Medium |
16531414
|
| 2010 |
ERLEC1/CIM sequesters OS-9 away from the HIF-1α complex and PHD2, thereby preventing HIF-1α degradation and permitting HIF-1α accumulation under hypoxic conditions. ERLEC1 also modulates the unfolded protein response through interaction with the key ER stress protein BiP, influencing cell proliferation under ER stress. |
Proteomic approaches, co-immunoprecipitation, ectopic expression, hypoxia tolerance assays |
Cancer research |
Medium |
21118962
|
| 2013 |
ERLEC1 expression is transcriptionally upregulated by ER stress via a novel ERSE-26 element (CCAAT-N26-CCACG) in its promoter, regulated by XBP1 but not ATF6α. XBP1 overexpression increased and siRNA knockdown of XBP1 reduced ERLEC1 mRNA levels. |
Luciferase reporter assays, ER stressor treatment (brefeldin A, tunicamycin, thapsigargin), siRNA knockdown of XBP1, mRNA quantification |
The Journal of biological chemistry |
Medium |
23737521
|
| 2021 |
XTP3-B/ERLEC1 stabilizes SEL1L by inhibiting its degradation. When proteasome activity is inhibited, SEL1L generates degradation intermediates that interact with aggregation-prone proteins including polyglutamine-expanded Huntingtin (Htt-polyQ-GFP), stimulating their cytosolic aggregation. |
Proteasome inhibitor assays, co-immunoprecipitation, GFP-tagged aggregation reporters, siRNA knockdown of OS-9 and XTP3-B |
The FEBS journal |
Medium |
33576152
|
| 2021 |
ERLEC1 is identified as a substrate for the ER translocation inhibitor cyclotriazadisulfonamide (CADA). CADA inhibits ERLEC1 protein expression in a signal peptide-dependent manner. Cell-free in vitro translation/translocation assays confirmed that ERLEC1's signal peptide is a target for CADA-mediated cotranslational translocation inhibition at the Sec61 translocon. |
Quantitative proteomics (SILAC-MS), Western blot, flow cytometry, cell-free in vitro translation/translocation assay |
Molecular & cellular proteomics |
Medium |
34481949
|
| 2023 |
SEL1L recruits ERLEC1 (along with OS9, UBE2J1, and DERLIN) to HRD1 to form a functional HRD1 ERAD complex. Attenuation of the SEL1L-HRD1 interaction (via a SEL1L variant) impairs recruitment of ERLEC1 to HRD1, demonstrating that SEL1L-HRD1 interaction is prerequisite for ERLEC1 incorporation into the functional ERAD complex. |
Proteomic interactome screens of SEL1L and HRD1, co-immunoprecipitation, knockin mouse model with SEL1L variant |
bioRxivpreprint |
Medium |
37333389
|
| 2023 |
Mutation of erlec1 in zebrafish results in further suppression of the cholesterol biosynthesis pathway in the context of misfolded Z-variant alpha1-antitrypsin (ZAAT) expression, confirming a role for this ER lectin in targeting misfolded ZAAT for ER-associated degradation (ERAD). |
CRISPR/Cas9 erlec1 knockout in zebrafish, transcriptomic and proteomic analysis |
International journal of molecular sciences |
Medium |
36768797
|
| 2011 |
EDEM1 overexpression or its up-regulation by IRE1 can deliver ERAD substrates to XTP3-B and OS9 even when mannose trimming is bypassed. An EDEM1 deletion mutant lacking most of the carbohydrate-recognition domain still accelerates ERAD by delivering substrate to XTP3-B, suggesting that substrate delivery from EDEM1 to XTP3-B can occur through protein-protein interactions independent of glycan recognition. |
siRNA knockdown, overexpression, pulse-chase degradation assays, confocal colocalization, co-immunoprecipitation |
Molecular biology of the cell |
Medium |
21917589
|
| 2020 |
Rare missense variants in ERLEC1 (including p.His413Tyr, p.Thr140Ser, p.Thr140Ile, p.Asn483Ser) co-segregate with Class III malocclusion. ERLEC1 is highly expressed in mouse jaw osteoblasts and inhibits osteoblast proliferation; the His413Tyr variant significantly enhanced this inhibitory effect on osteoblast proliferation. Proper ERLEC1 expression level is required for correct osteogenic differentiation. |
Exome sequencing, Sanger sequencing co-segregation, ERLEC1 expression analysis in osteoblasts, overexpression of wild-type vs. mutant ERLEC1 with cell proliferation and differentiation assays |
Human mutation |
Medium |
32442352
|