Affinage

PPP2R3C

Serine/threonine-protein phosphatase 2A regulatory subunit B'' subunit gamma · UniProt Q969Q6

Length
453 aa
Mass
53.3 kDa
Annotated
2026-06-10
23 papers in source corpus 13 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PPP2R3C (G5PR/G4-1) is a non-catalytic regulatory/adaptor subunit that bridges the serine/threonine phosphatases PP2A and PP5 to specific phosphorylated targets, thereby restraining stress and kinase signaling across immune, developmental, and centrosomal contexts (PMID:12167160, PMID:20925653). It associates with the PP2A A/C subunits and with PP5 through a TPR-domain interaction, forming a complex with phosphatase activity in vitro (PMID:12167160). A recurring theme of its biology is suppression of JNK signaling: conditional deletion in B cells and thymocytes causes hyperactivation of JNK and downstream apoptotic effectors (Bim in B cells; Caspase-3 and FasL in thymocytes), driving activation-induced and developmental cell death, whereas its induction or overexpression dampens late-phase JNK to promote B-cell survival and differentiation (PMID:16129705, PMID:18022237, PMID:22753944). As an adaptor it recruits PP5 to substrate phosphosites — to the autophosphorylated serine-rich C-terminus of activated IKKβ to down-regulate NF-κB (PMID:20925653), and to phosphorylated P-glycoprotein (ABCB1) to reduce its expression and drug efflux activity (PMID:24333728). At the distal centriole it partners with CEP350 and FOP and counteracts the kinase MAP3K1 to maintain centrosome integrity and limit JNK signaling, with a disease variant defective in centriolar localization and FOP binding (PMID:39317195, PMID:38617270); it analogously antagonizes MEKK1 to control Gli phosphorylation and positively regulates Hedgehog target-gene expression (PMID:39173855). Homozygous missense variants in PPP2R3C cause syndromic 46,XY/XX gonadal dysgenesis with reduced phospho-SOX9 in dysgenetic gonads, and complete loss is embryonic lethal in mice (PMID:30893644, PMID:34714774).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2002 Medium

    Established the founding biochemical identity of PPP2R3C as a phosphatase-associated subunit, answering what enzymatic machinery it engages.

    Evidence Yeast two-hybrid, reciprocal pull-downs, and in vitro phosphatase assays in transfectants showing TPR-mediated association with PP2A (A/C subunits) and PP5

    PMID:12167160

    Open questions at the time
    • G5PR alone neither stimulated nor inhibited PP2A/PP5 activity, leaving its regulatory mechanism on phosphatase activity undefined
    • no physiological substrate identified at this stage
    • cell-cycle-dependent localization not linked to a function
  2. 2005 High

    Defined a physiological requirement for PPP2R3C in restraining JNK-driven apoptosis, showing the subunit has a discrete cellular survival function rather than a generic housekeeping role.

    Evidence B-cell conditional knockout (CD19-Cre) with proliferation/apoptosis assays and signaling western blots; plus transcriptional induction analysis and cDNA rescue in WEHI-231 cells

    PMID:16129705 PMID:16343422

    Open questions at the time
    • did not establish which phosphatase (PP2A vs PP5) mediates JNK suppression
    • direct dephosphorylation target in the JNK pathway not identified
    • selectivity for JNK over Erk/NF-κB/Akt mechanistically unexplained
  3. 2007 High

    Showed the JNK-restraining function operates in a cell-type-specific manner, controlling a JNK-Caspase-3 apoptotic pathway in thymocytes distinct from the Bim-dependent route in B cells.

    Evidence T-cell-specific conditional knockout with flow cytometry, apoptosis assays, and western blotting for JNK, Caspase-3, Bim, FasL

    PMID:18022237

    Open questions at the time
    • why Bim is engaged in B cells but not thymocytes is unresolved
    • molecular substrate upstream of JNK not defined
    • no biochemical reconstitution of the phosphatase-JNK axis
  4. 2011 High

    Resolved the molecular adaptor mechanism, demonstrating PPP2R3C bridges PP5 to a phosphorylated substrate to terminate signaling.

    Evidence Co-IP with domain-mapping mutagenesis of IKKβ phospho-serines, siRNA knockdown of G4-1 and PP5, and NF-κB reporter assays under TNFα

    PMID:20925653

    Open questions at the time
    • structural basis of phospho-IKKβ recognition not determined
    • whether the same adaptor logic explains JNK regulation untested
    • in vivo relevance of the NF-κB axis not addressed
  5. 2012 High

    Demonstrated gain-of-function consequences in vivo, linking PPP2R3C-mediated JNK suppression to B-cell survival, impaired affinity maturation, and autoimmunity.

    Evidence Transgenic overexpression mouse with immunohistochemistry, flow cytometry, in vitro AICD and JNK assays, and antibody affinity measurement

    PMID:22753944

    Open questions at the time
    • mechanism connecting JNK suppression to autoantibody production not dissected
    • phosphatase substrate(s) controlling late-phase JNK unknown
  6. 2013 Medium

    Extended the PP5-adaptor role beyond immune signaling, identifying P-glycoprotein as a substrate whose dephosphorylation modulates multidrug resistance.

    Evidence Co-IP, in vitro dephosphorylation of PKA/PKC-phosphorylated P-gp, siRNA knockdown with vincristine/doxorubicin cytotoxicity assays

    PMID:24333728

    Open questions at the time
    • specific phospho-residues on P-gp dephosphorylated not mapped
    • single lab without reciprocal in vivo validation
    • PP2A excluded but PP5 contribution not quantitatively separated from PPP2R3C
  7. 2015 Medium

    Causally linked PPP2R3C-driven JNK suppression to B1a-cell-to-plasmablast differentiation using pharmacological phenocopy.

    Evidence Transgenic B1a-cell culture with JNK inhibitor SP600125 recapitulation, ELISA for autoantibody, flow cytometry

    PMID:25601926

    Open questions at the time
    • direct phosphatase substrate in B1a JNK pathway unidentified
    • single-lab gain-of-function system
  8. 2019 Medium

    Established a human Mendelian disease link, implicating PPP2R3C in SOX9 phospho-signaling during testis development.

    Evidence Exome/Sanger sequencing of a patient cohort with homozygous missense variants plus phospho-SOX9 immunohistochemistry of dysgenetic gonads

    PMID:30893644

    Open questions at the time
    • no in vitro reconstitution of variant effect on phosphatase function
    • direct phosphatase-SOX9 biochemical relationship not demonstrated
    • how each variant impairs the PP2A/PP5 complex unknown
  9. 2021 Medium

    Broadened the disease spectrum to both 46,XY and 46,XX dysgenesis and proved PPP2R3C is essential for embryonic viability.

    Evidence Sanger sequencing of patients with the recurrent p.L193S variant and CRISPR/Cas9 knockout mice with timed embryo inspection

    PMID:34714774

    Open questions at the time
    • embryonic lethality precludes tissue-specific developmental mechanism
    • molecular cause of early lethality (before 7.5 dpc) not defined
  10. 2024 High

    Defined a subcellular site and antagonist for PPP2R3C function, placing it at the distal centriole where it opposes MAP3K1 to preserve centrosome integrity, and identifying a parallel Gli/Hedgehog regulatory role.

    Evidence Functional genomics, centriolar immunofluorescence, genetic epistasis (MAP3K1 KO suppression), JNK assays, FOP/CEP350 binding, and disease-variant localization defect; plus Co-IP and Hh reporter/qPCR/proliferation assays for the Gli axis

    PMID:38617270 PMID:39173855 PMID:39317195

    Open questions at the time
    • whether PP2A or PP5 catalytic activity executes MAP3K1/Gli dephosphorylation at the centriole unresolved
    • direct phospho-substrate dephosphorylated to counter MAP3K1 not identified
    • link between centriolar function and gonadal/SOX9 phenotype not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how PPP2R3C selects between its PP2A and PP5 catalytic partners for each substrate and how a single adaptor coordinates JNK, NF-κB, Hedgehog, centrosomal, and SOX9 outputs.
  • no structural model of substrate-specific phosphatase targeting
  • direct catalytic substrate for the developmental/SOX9 phenotype unidentified
  • unifying biochemical logic across contexts undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0098772 molecular function regulator activity 3 GO:0140096 catalytic activity, acting on a protein 2
Localization
GO:0005634 nucleus 1 GO:0005815 microtubule organizing center 1 GO:0005829 cytosol 1
Pathway
R-HSA-168256 Immune System 3 GO:0140096 catalytic activity, acting on a protein 2 R-HSA-1266738 Developmental Biology 2 R-HSA-162582 Signal Transduction 2 R-HSA-5357801 Programmed Cell Death 2 R-HSA-1852241 Organelle biogenesis and maintenance 1
Partners
ABCB1CEP350FOPGLIIKBKBMAP3K1PPP2CAPPP5C
Complex memberships
PP2A holoenzyme (B''gamma regulatory subunit)PP5/PPP2R3C phosphatase complex

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 G5PR (PPP2R3C) was identified as a GANP-associated molecule via yeast two-hybrid screening. Pull-down assays demonstrated that G5PR associates with protein phosphatase 2A (PP2A; the A/PR65 and catalytic C subunits) and with protein phosphatase 5 (PP5) through its TPR domain. The G5PR-associated complex had phosphatase activity on casein, histone H1, and MCM3 in vitro, though addition of G5PR alone did not stimulate or inhibit PP5 or PP2A activities. G5PR cellular localization varied with cell cycle phase: nuclear during prophase, peri-chromatin during mitosis, and cytoplasmic after cell division. Yeast two-hybrid screening, in vivo co-immunoprecipitation in transfectants, pull-down assays, in vitro phosphatase activity assays, immunofluorescence localization Genes to cells : devoted to molecular & cellular mechanisms Medium 12167160
2005 Conditional knockout of G5pr in B cells (CD19-Cre) showed that G5PR is required for BCR-mediated proliferation and prevention of activation-induced cell death (AICD) in mature B cells. G5pr−/− B cells had increased mitochondrial membrane depolarization, enhanced JNK activation, and elevated Bim activation after BCR cross-linking, while Erk, NF-κB, cyclin D2, and Akt activation were normal. Conditional gene knockout (CD19-Cre), in vitro proliferation assays, flow cytometry, western blotting for signaling intermediates The Journal of experimental medicine High 16129705
2005 BCR cross-linking induced G5PR (PPP2R3C) transcription selectively in AICD-resistant mature splenic IgM-lo IgD-hi B cells but not in AICD-susceptible immature B cells. G5pr cDNA transfection protected the immature B-cell line WEHI-231 from BCR-mediated AICD, and lack of G5PR upregulation correlated with prolonged JNK activation. RT-PCR/northern analysis of B-cell subsets, cDNA transfection rescue experiment, JNK activation assays Biochemical and biophysical research communications Medium 16343422
2007 T-cell-specific G5PR knockout mice displayed thymic atrophy and ~10-fold reduction in CD4/CD8 double-positive (DP) thymocytes with few mature single-positive cells. G5pr−/− thymocytes showed normal DN-to-DP transition but increased apoptosis at the DP stage, associated with hyper-activation of JNK and Caspase-3 and augmented FasL expression, but no change in Bim activation, demonstrating that G5PR controls a JNK-Caspase-3 apoptotic pathway specific to thymocytes. T-cell-specific conditional knockout, flow cytometry, apoptosis assays, western blotting for JNK, Caspase-3, Bim, FasL Molecular immunology High 18022237
2011 G4-1 (PPP2R3C) physically interacts with IKKβ in a manner dependent on IKKβ kinase activity. The serine-rich C-terminal domain of IKKβ (containing seven autophosphorylated serines) is required for G4-1 binding; mutating these serines to alanine abolished G4-1 binding and rendered IKKβ more potent at activating NF-κB. G4-1 knockdown enhanced TNFα-induced NF-κB activity. G4-1 functions as an adaptor that recruits PP5 to the phosphorylated C-terminus of activated IKKβ to down-regulate IKKβ activity; knockdown of PP5 abolished the inhibitory activity of G4-1 on NF-κB activation. Co-immunoprecipitation, domain-mapping mutagenesis, siRNA knockdown, NF-κB reporter assays, TNFα stimulation The Biochemical journal High 20925653
2012 G5PR (PPP2R3C) is upregulated in Ki67-negative centrocytes at germinal centers and in mature GC B cells after immunization. Transgenic overexpression of G5PR led to augmented GC B cell generation via increase in non-antigen-specific B cells, impaired affinity maturation, suppression of late-phase JNK activation, and rescue of B-1a cells from AICD in vitro. Aged female G5PR-transgenic mice developed peritoneal B-1a cell expansion and autoantibody production. Transgenic mouse model, immunohistochemistry, flow cytometry, in vitro AICD assays, JNK phosphorylation assays, anti-NP antibody affinity measurement Journal of immunology (Baltimore, Md. : 1950) High 22753944
2013 PPP2R3C was identified as a binding candidate for P-glycoprotein (ABCB1) by immunoprecipitation-western blotting; PP5 and PPP2R3C co-precipitated with P-gp but PP2A did not. The PP5/PPP2R3C complex dephosphorylated PKA/PKC-mediated phosphorylation of P-gp. Knockdown of PP5 and/or PPP2R3C increased P-gp expression and reduced sensitivity to vincristine and doxorubicin. Co-immunoprecipitation, western blotting, siRNA knockdown, in vitro dephosphorylation assay, cytotoxicity assay Cancer letters Medium 24333728
2015 G5PR overexpression in B1a cells suppressed BCR-mediated JNK signaling and drove differentiation of peritoneal B1a cells into IgM and IgG autoantibody-secreting plasmablasts in vitro. JNK inhibitor SP600125 recapitulated this effect in wild-type B1a cells, establishing that G5PR-mediated JNK suppression promotes B1a-to-plasmablast differentiation. G5PR-transgenic mouse B1a cell isolation, iGB culture system with IL-4/CD40L/BAFF, JNK inhibitor treatment, ELISA for autoantibody secretion, flow cytometry Journal of immunology (Baltimore, Md. : 1950) Medium 25601926
2019 Homozygous missense variants in PPP2R3C (p.L103P, p.L193S, p.F350S) cause 46,XY complete gonadal dysgenesis. Immunohistochemistry of dysgenetic gonads from patients showed decreased SOX9-phosphoprotein expression, implicating PPP2R3C in SOX9 phospho-signaling during testis development. Heterozygous males showed abnormal sperm morphology and impaired fertility. Exome/Sanger sequencing of patient cohort, immunohistochemistry for phospho-SOX9 in gonadal tissue European journal of endocrinology Medium 30893644
2021 Homozygous PPP2R3C p.L193S variant causes broad-spectrum gonadal dysgenesis in both 46,XY and 46,XX individuals. CRISPR/Cas9-generated homozygous Ppp2r3c knockout mice died during early embryogenesis (at or before 7.5 dpc), demonstrating that Ppp2r3c is essential for embryonic viability in mice. Sanger sequencing of patients, CRISPR/Cas9 knockout mice with timed embryo inspections European journal of endocrinology Medium 34714774
2024 PPP2R3C is a distal centriole protein that localizes to centrosomes and functionally partners with centriolar proteins CEP350 and FOP. PPP2R3C counteracts the kinase activity of MAP3K1 at centrosomes: MAP3K1 knockout suppresses growth defects caused by PPP2R3C inactivation, and the two have opposing effects on basal and microtubule stress-induced JNK signaling. A disease-associated PPP2R3C variant is defective in centriolar localization and FOP binding. Acute MAP3K1 overexpression caused rapid centriole disintegration, phenocopying PPP2R3C loss. Systems genetics (functional genomic analyses), immunofluorescence/microscopy for centriolar localization, genetic epistasis (MAP3K1 KO suppression), JNK signaling assays, co-localization/binding studies with FOP and CEP350, disease variant analysis Current biology : CB High 38617270 39317195
2024 PPP2R3C (B″gamma subunit of PP2A) interacts with Gli proteins and acts as a positive regulator of Hedgehog signaling. PPP2R3C disruption reduced expression of Gli1/2 and Hh target genes upon pathway activation and reduced growth of a Hh-dependent medulloblastoma cell line. An antagonistic relationship was established between PPP2R3C and MEKK1 kinase in regulating Gli protein phosphorylation. Co-immunoprecipitation (PPP2R3C-Gli interaction), siRNA/CRISPR knockdown with Hh pathway reporter assays and target gene qPCR, cell proliferation assays, phosphorylation analysis of Gli Cellular signalling Medium 39173855

Source papers

Stage 0 corpus · 23 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1989 Characterization of a subclone (D10S) of the D10.G4.1 helper T-cell line which proliferates to attomolar concentrations of interleukin-1 in the absence of mitogens. Cytokine 62 2535250
2004 Neuromedin U elicits cytokine release in murine Th2-type T cell clone D10.G4.1. Journal of immunology (Baltimore, Md. : 1950) 46 15585845
2002 MCM3-binding GANP DNA-primase is associated with a novel phosphatase component G5PR. Genes to cells : devoted to molecular & cellular mechanisms 27 12167160
1995 Comparison of the mechanisms regulating IL-5, IL-4, and three other lymphokine genes in the Th2 clone D10.G4.1. Experimental hematology 27 7601249
2013 Protein phosphatase complex PP5/PPP2R3C dephosphorylates P-glycoprotein/ABCB1 and down-regulates the expression and function. Cancer letters 25 24333728
2019 PPP2R3C gene variants cause syndromic 46,XY gonadal dysgenesis and impaired spermatogenesis in humans. European journal of endocrinology 24 30893644
2005 Protein phosphatase subunit G5PR is needed for inhibition of B cell receptor-induced apoptosis. The Journal of experimental medicine 23 16129705
1995 Effect of phosphodiesterase inhibition on IL-4 and IL-5 production of the murine TH2-type T cell clone D10.G4.1. Immunopharmacology 21 8557518
2007 Protein phosphatase subunit G5PR that regulates the JNK-mediated apoptosis signal is essential for the survival of CD4 and CD8 double-positive thymocytes. Molecular immunology 12 18022237
1993 In vitro immunization of mouse spleen cells for the production of monoclonal IgG1 antibodies using an antigen-specific T helper cell clone (D.10.G4.1). Journal of immunological methods 12 7507145
2012 Transgenic overexpression of G5PR that is normally augmented in centrocytes impairs the enrichment of high-affinity antigen-specific B cells, increases peritoneal B-1a cells, and induces autoimmunity in aged female mice. Journal of immunology (Baltimore, Md. : 1950) 9 22753944
2011 Phosphorylation-dependent association of the G4-1/G5PR regulatory subunit with IKKβ negatively modulates NF-κB activation through recruitment of protein phosphatase 5. The Biochemical journal 8 20925653
2022 Case Report: Novel Compound Heterozygotic Variants in PPP2R3C Gene Causing Syndromic 46, XY Gonadal Dysgenesis and Literature Review. Frontiers in genetics 7 35812758
2005 BCR-crosslinking induces a transcription of protein phosphatase component G5PR that is required for mature B-cell survival. Biochemical and biophysical research communications 7 16343422
1995 Effect of pharmacological agents on the productions of interleukin-10 by the murine D10.G4.1 TH2 cell line in vitro. International journal of immunopharmacology 6 8586491
2021 Broad-spectrum XX and XY gonadal dysgenesis in patients with a homozygous L193S variant in PPP2R3C. European journal of endocrinology 5 34714774
2015 JNK regulatory molecule G5PR induces IgG autoantibody-producing plasmablasts from peritoneal B1a cells. Journal of immunology (Baltimore, Md. : 1950) 5 25601926
1996 Differential effect of the activation of protein kinase A on the protein synthesis and secretion in the T-helper 2 cell line D10.G4.1. Scandinavian journal of immunology 4 8711428
1993 The I-Ab-restricted alloresponse of D10.G4.1 T cells is based on the recognition of an endogenous peptide. Immunology 4 8495978
2024 PP2A phosphatase regulatory subunit PPP2R3C is a new positive regulator of the hedgehog signaling pathway. Cellular signalling 2 39173855
2024 A disease-associated PPP2R3C-MAP3K1 phospho-regulatory module controls centrosome function. Current biology : CB 2 39317195
1993 Enhanced IL-4-mediated D10.G4.1 proliferation with suboptimal concentrations of anti-IL-4 receptor monoclonal antibodies. Journal of immunology (Baltimore, Md. : 1950) 2 8419473
2024 A disease-associated PPP2R3C-MAP3K1 phospho-regulatory module controls centrosome function. bioRxiv : the preprint server for biology 0 38617270

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