Affinage

PREX2

Phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 2 protein · UniProt Q70Z35

Length
1606 aa
Mass
182.6 kDa
Annotated
2026-04-28
31 papers in source corpus 18 papers cited in narrative 18 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PREX2 is a PIP3- and Gβγ-activated guanine-nucleotide exchange factor (GEF) for RAC1 that integrates PI3K and G-protein signaling to regulate cytoskeletal remodeling, insulin/glucose metabolism, and synaptic plasticity. PREX2 forms a mutual inhibitory complex with PTEN, in which the PREX2 PH domain blocks PTEN phosphatase activity while PTEN allosterically promotes PREX2 autoinhibition and occludes Gβγ binding, with PTEN anchored via its C-terminal PDZ-interacting motif to the second PDZ domain of PREX2 (PMID:33947796, PMID:24367090, PMID:25829446); this complex is positively modulated by AHCYL1 (PMID:40365293) and negatively regulated by PAK-mediated phosphorylation that reduces PREX2 membrane recruitment (PMID:26438819) and GNMT/HectH9-mediated proteasomal degradation (PMID:28205209). In vivo, PREX2 is required for cerebellar Purkinje cell dendrite morphology and motor coordination (PMID:18334636), and suppresses hepatic and skeletal-muscle glucose uptake through a GEF-independent adaptor function controlling GLUT2 surface levels and GPR21 trafficking (PMID:40764335). Cancer-associated PREX2 mutations escape PTEN-mediated inhibition to drive constitutive RAC1/PI3K–AKT signaling and confer resistance to MAPK pathway inhibitors in melanoma (PMID:25829446, PMID:39636745).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2004 High

    Establishing the core enzymatic identity of PREX2 as a Rac-GEF synergistically activated by PIP3 and Gβγ answered the fundamental question of what this multi-domain protein does biochemically and placed it at the intersection of PI3K and GPCR signaling.

    Evidence In vitro and in vivo GEF activity assays with PIP3/Gβγ stimulation, reported simultaneously by two independent groups

    PMID:15304342 PMID:15304343

    Open questions at the time
    • Substrate specificity beyond Rac1 not tested
    • Structural basis of PIP3/Gβγ synergy unknown
    • Tissue-specific functions uncharacterized
  2. 2008 High

    Generation of P-Rex2 knockout mice revealed its first physiological role — maintaining Purkinje cell dendrite morphology and motor coordination — demonstrating that PREX2 is not redundant with the related P-Rex1 in the cerebellum.

    Evidence P-Rex2 knockout and P-Rex1/P-Rex2 double-knockout mice with histological and behavioral analysis

    PMID:18334636

    Open questions at the time
    • Whether the Purkinje cell phenotype is Rac1-GEF-dependent or adaptor-mediated was not distinguished
    • Downstream effectors in dendrite morphogenesis not identified
  3. 2012 Medium

    The discovery that PREX2 binds and inhibits PTEN, and that PREX2 is recurrently mutated in melanoma, reframed the gene as an oncogenic regulator of the PI3K/AKT axis rather than solely a Rac-GEF.

    Evidence Whole-genome sequencing of melanomas; ectopic PREX2 expression in NRAS-mutant melanocytes with in vivo tumor formation assay

    PMID:22622578

    Open questions at the time
    • Independent replication of tumor acceleration failed
    • Whether PTEN inhibition or Rac activation drives tumorigenic phenotype was unresolved
  4. 2013 High

    Mapping the two-interface interaction between PREX2 and PTEN (PH domain–PTEN catalytic region and IP4P domain–PTEN PDZ-binding domain), and showing that Prex2 loss increases PTEN activity and impairs insulin signaling in vivo, established the molecular logic of mutual inhibition and its metabolic relevance.

    Evidence Domain mapping, co-immunoprecipitation, Prex2 knockout mouse with insulin signaling and glucose uptake assays

    PMID:24367090

    Open questions at the time
    • Structural resolution of the interface lacking
    • Mechanism linking PTEN C-terminal phosphorylation to PH domain release incompletely defined
  5. 2015 High

    Two studies resolved opposite arms of the mutual inhibition: PTEN inhibits PREX2 GEF activity via its C-terminal tail (independently of phosphatase activity), and cancer-derived PREX2 mutants escape this inhibition; simultaneously, PAK-mediated phosphorylation of PREX2 was identified as a negative feedback loop that reduces PIP3/Gβγ binding and membrane localization after Rac1 activation.

    Evidence In vitro fluorescent nucleotide exchange assays with mutant panels, cell invasion assays; in vitro GEF assays with PAK phosphorylation, mass spectrometry phosphosite mapping, cell fractionation

    PMID:25829446 PMID:26438819

    Open questions at the time
    • PAK phosphorylation sites not mapped to structural domains
    • Whether PTEN tail inhibition is allosteric or steric was unclear
  6. 2017 High

    Identification of GNMT–HectH9(HUWE1)-mediated proteasomal ubiquitination as the mechanism controlling PREX2 protein turnover added a proteostatic regulatory layer and explained how GNMT suppresses AKT signaling.

    Evidence Reciprocal co-immunoprecipitation, ubiquitination assays, siRNA knockdown of GNMT and HectH9

    PMID:28205209

    Open questions at the time
    • Ubiquitination sites on PREX2 not mapped
    • Whether ubiquitination is constitutive or signal-regulated not determined
  7. 2018 High

    The 1.9 Å crystal structure of the P-Rex2 PH domain showed that PIP3 binding is essential for GEF activity but not membrane localization, distinguishing lipid-dependent activation from membrane targeting.

    Evidence X-ray crystallography and biochemical PIP3 binding assays

    PMID:34958187

    Open questions at the time
    • Structure of remaining domains and full-length protein not resolved
    • PIP3-induced conformational changes in the DH-PH tandem not visualized
  8. 2021 High

    Cross-linking mass spectrometry of the PTEN–P-Rex2 complex provided a near-complete structural model of their mutual inhibition: PTEN's PDZ-interacting motif anchors to the second PDZ domain of P-Rex2, positioning PTEN to block PIP3 hydrolysis, while PTEN allosterically stabilizes P-Rex2 autoinhibition and blocks Gβγ binding.

    Evidence Cross-linking mass spectrometry, functional GEF and phosphatase activity assays with targeted mutations

    PMID:33947796

    Open questions at the time
    • High-resolution atomic model of the full complex not available
    • Dynamics of complex assembly and disassembly upon signaling not characterized
  9. 2022 Medium

    PREX2's role was extended to synaptic plasticity, showing that P-Rex2 activates Rac1 in dorsal horn neurons to phosphorylate GluR1 and promote AMPA receptor trafficking during bone cancer pain, establishing a neuronal signaling function beyond cerebellum.

    Evidence In vivo lentiviral knockdown, patch-clamp electrophysiology, spine morphology analysis in dorsal horn neurons

    PMID:35083941

    Open questions at the time
    • Direct GEF activity measurement in these neurons lacking
    • Relevance to non-pain synaptic plasticity not tested
  10. 2025 High

    Use of catalytically-inactive Prex2 knockin mice demonstrated that PREX2 suppresses glucose uptake in liver and skeletal muscle through a GEF-independent adaptor function, controlling GLUT2 surface levels and GPR21 trafficking — a fundamentally new mode of action for PREX2.

    Evidence Prex2 KO and catalytically-inactive Prex2GD knockin mice with glucose uptake, GLUT2 surface, mitochondrial ATP, and GPR21 trafficking assays

    PMID:40764335

    Open questions at the time
    • Adaptor-binding partners mediating GLUT2/GPR21 trafficking not identified
    • How GEF-independent and GEF-dependent functions are coordinated in vivo unknown
  11. 2025 Medium

    Genetic loss of PREX2 sensitizes BRAF-mutant melanoma to MAPK inhibitors, with PI3Kβ inhibition phenocopying PREX2 deficiency, defining a druggable PREX2–RAC1–PI3Kβ signaling axis in therapy resistance.

    Evidence Genetically engineered mouse melanoma models, patient-derived cell lines, pharmacologic PI3Kβ inhibition

    PMID:39636745

    Open questions at the time
    • Whether PREX2 directly activates PI3Kβ or acts via RAC1 not resolved
    • Clinical validation in patient cohorts lacking

Open questions

Synthesis pass · forward-looking unresolved questions
  • A high-resolution structure of the full-length PREX2–PTEN complex and the molecular basis of PREX2's GEF-independent adaptor functions remain the central unresolved mechanistic questions.
  • No atomic-resolution structure of full-length PREX2 in complex with PTEN
  • Adaptor-mode binding partners and structural basis for GLUT2/GPR21 regulation unknown
  • In vivo regulation of PREX2 at different tissues (brain vs. liver vs. muscle) not integrated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 6 GO:0098772 molecular function regulator activity 3 GO:0060090 molecular adaptor activity 1
Localization
GO:0005886 plasma membrane 2 GO:0005829 cytosol 1
Pathway
R-HSA-162582 Signal Transduction 8 R-HSA-1643685 Disease 4 R-HSA-1266738 Developmental Biology 1
Partners
AHCYL1CELF2GNMTGPR21HUWE1PAK1PTENRAC1
Complex memberships
PREX2–PTEN complex

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2004 PREX2 (P-Rex2) is a guanine-nucleotide exchange factor (GEF) that activates the small GTPase Rac and is synergistically regulated by PIP3 and Gβγ subunits of heterotrimeric G proteins in vitro and in vivo. GEF activity assays, in vitro and in vivo Rac activation assays FEBS letters High 15304342 15304343
2004 PREX2 activates Rac in a PI3K-dependent manner, linking it to the PI3K signaling pathway. GTP-bound Rac measurement after PI3K stimulation FEBS letters High 15304342 15304343
2008 P-Rex2 is specifically expressed in cerebellar Purkinje neurons and is required for normal Purkinje cell dendrite morphology; P-Rex2 knockout mice exhibit thinned main dendrites in Purkinje cells and progressive motor coordination defects. P-Rex2 knockout mouse generation, histological analysis of Purkinje cell morphology, behavioral motor tests Proceedings of the National Academy of Sciences of the United States of America High 18334636
2012 PREX2 is a PTEN-interacting protein and negative regulator of PTEN; somatic PREX2 mutations at ~14% frequency in melanoma accelerate tumor formation of immortalized human melanocytes in vivo. Whole-genome sequencing, ectopic expression in NRASG12D melanocytes, in vivo tumor formation assay Nature Medium 22622578
2013 P-REX2 inhibits PTEN via two interfaces: the PH domain of P-REX2 inhibits PTEN by interacting with the catalytic region of PTEN, and the IP4P domain provides high-affinity binding to the PDZ-binding domain of PTEN. P-REX2 inhibition of PTEN requires C-terminal phosphorylation of PTEN to release the P-REX2 PH domain from its neighboring DH domain. Prex2 deletion in mice increases Pten activity and decreases insulin signaling in liver and adipose tissue, leading to reduced glucose uptake and insulin resistance. Domain mapping, co-immunoprecipitation, Prex2 knockout mouse, insulin signaling assays, glucose uptake assays Proceedings of the National Academy of Sciences of the United States of America High 24367090
2015 PTEN inhibits PREX2 GEF activity toward RAC1 via its C-terminal tail domain (independent of PTEN lipid phosphatase activity). Cancer-derived somatic PREX2 mutants are resistant to PTEN-mediated inhibition of invasion, with two mutants escaping GEF inhibition and a third showing reduced PTEN binding affinity. Fluorescent nucleotide exchange assays (in vitro GEF activity), cell invasion assays, co-immunoprecipitation, mouse embryonic fibroblasts and breast cancer cell lines Science signaling High 25829446
2015 PAK kinases phosphorylate PREX2 following Rac1 activation, reducing PREX2 GEF activity toward Rac1 by inhibiting PREX2 binding to PIP3 and Gβγ. PAK-mediated phosphorylation also prevents PREX2 membrane localization, constituting a negative feedback loop on Rac1 signaling downstream of insulin. In vitro GEF assays, cell fractionation, mass spectrometry phosphosite identification, PAK inhibitor experiments, insulin stimulation assays The Journal of biological chemistry High 26438819
2017 GNMT interacts with PREX2 and promotes its degradation through an HectH9 (HUWE1) E3 ligase-mediated proteasomal ubiquitination pathway. Depletion of GNMT or HectH9 leads to elevated PREX2 protein and AKT activation. Co-immunoprecipitation, ubiquitination assays, siRNA knockdown, protein stability assays International journal of cancer High 28205209
2018 Crystal structure of the P-Rex2 PH domain at 1.9 Å reveals conformational differences in loop regions compared to P-Rex1. The P-Rex2 PH domain binds PIP3 similarly to P-Rex1, and PIP3 binding is critical for P-Rex2 GEF activity but not membrane localization. X-ray crystallography, biochemical PIP3 binding assays Journal of structural biology: X High 34958187
2019 The PREX2 gain-of-function mutation S1113R, identified in HCC, enhances PREX2 protein stability by impairing HectH9-mediated ubiquitination, promotes cell migration, and activates the AKT pathway. Protein half-life assays, ubiquitination assays, cell migration assays, AKT phosphorylation western blot Scientific reports Medium 30796242
2020 CELF2 interacts with PREX2 and reduces the association of PREX2 with PTEN, thereby upregulating PTEN phosphatase activity and repressing AKT phosphorylation. This represents a mechanism by which CELF2 antagonizes the oncogenic effect of PREX2. Co-immunoprecipitation, PTEN phosphatase activity assay, AKT phosphorylation assay, PDX tumor model Carcinogenesis Medium 31241130
2021 Cross-linking mass spectrometry and functional studies revealed the structural basis of PTEN:P-Rex2 complex assembly: PTEN is anchored to P-Rex2 via interactions between the PTEN C-terminal PDZ-interacting motif and the second PDZ domain of P-Rex2, bridging PTEN across the P-Rex2 surface to prevent PI(3,4,5)P3 hydrolysis. Conversely, PTEN allosterically promotes an autoinhibited P-Rex2 conformation and blocks Gβγ binding to P-Rex2. Cross-linking mass spectrometry, functional GEF and phosphatase activity assays, mutagenesis Science signaling High 33947796
2022 P-Rex2 mediates synaptic plasticity in bone cancer pain by activating Rac1 and phosphorylating GluR1, promoting GluR1-containing AMPA receptor trafficking and spine morphology changes in dorsal horn neurons. RNAi lentivirus knockdown in vivo, western blot for p-Rac1 and p-GluR1, spine counting, patch-clamp electrophysiology Molecular pain Medium 35083941
2024 PREX2 promotes radioresistance in colorectal cancer by facilitating DNA repair through upregulation of DNA-PKcs and suppressing radiation-induced immunogenic cell death by inhibiting the cGAS/STING/IFNs pathway, thereby impeding CD8+ T cell infiltration. RNA-seq, colony formation assay, comet assay, apoptosis assay, western blot, xenograft mouse models, PREX2 inhibitor (PREX-in1) BMC medicine Medium 38609982
2025 AHCYL1 is a novel PREX2-interacting protein that enhances PREX2 GEF activity toward RAC1 by alleviating the mutual inhibition between PREX2 and PTEN. Pull-down assay, LC-MS/MS, in vitro GEF assay, active RAC1 pull-down assay, western blotting Theranostics Medium 40365293
2025 P-Rex2 suppresses glucose uptake into liver and skeletal muscle independently of its Rac-GEF catalytic activity (demonstrated using catalytically-inactive Prex2GD knockin mice). In hepatocytes, P-Rex2 suppresses Glut2 surface levels and mitochondrial ATP production, and controls trafficking of the orphan GPCR Gpr21. In skeletal muscle, P-Rex2 suppresses glucose uptake via a separate adaptor function independent of Gpr21. Prex2 knockout and catalytically-inactive Prex2GD knockin mice, glucose uptake assays, Glut2 surface assay, mitochondrial membrane potential assay, Gpr21 trafficking assay Scientific reports High 40764335
2025 Genetic loss of PREX2 in BRAF-mutant melanoma confers sensitivity to MAPK pathway inhibitors, and PREX2 acts upstream of RAC1 and PI3Kβ in a druggable signaling axis; pharmacological PI3Kβ inhibition phenocopies PREX2 deficiency. Genetically engineered mouse models, patient-derived melanoma cell lines, genetic and pharmacologic PI3Kβ inhibition, BRAF inhibitor sensitivity assays Cancer research Medium 39636745
2026 Cryo-EM structure of full-length P-Rex2 reveals that while the overall structure resembles P-Rex1, there is a substantial repositioning of the N-terminal module relative to the C-terminal core, potentially precluding the intramolecular N-terminal/C-terminal interactions seen in autoinhibited P-Rex1. HDX-MS shows P-Rex2 dynamics are unaffected by IP4 (PIP3 headgroup), unlike P-Rex1, suggesting a distinct autoinhibition mechanism. Cryo-EM, hydrogen-deuterium exchange mass spectrometry (HDX-MS), SEC-SAXS, biochemical GEF assays bioRxivpreprint Medium 41542420

Source papers

Stage 0 corpus · 31 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 Melanoma genome sequencing reveals frequent PREX2 mutations. Nature 588 22622578
2004 P-Rex2, a new guanine-nucleotide exchange factor for Rac. FEBS letters 88 15304343
2004 P-REX2, a novel PI-3-kinase sensitive Rac exchange factor. FEBS letters 82 15304342
2015 PTEN inhibits PREX2-catalyzed activation of RAC1 to restrain tumor cell invasion. Science signaling 62 25829446
2008 P-Rex2 regulates Purkinje cell dendrite morphology and motor coordination. Proceedings of the National Academy of Sciences of the United States of America 58 18334636
2013 Regulation of PTEN inhibition by the pleckstrin homology domain of P-REX2 during insulin signaling and glucose homeostasis. Proceedings of the National Academy of Sciences of the United States of America 57 24367090
2020 CELF2 suppresses non-small cell lung carcinoma growth by inhibiting the PREX2-PTEN interaction. Carcinogenesis 43 31241130
2017 P-Rex1 and P-Rex2 RacGEFs and cancer. Biochemical Society transactions 38 28710285
2017 Characterization of the GNMT-HectH9-PREX2 tripartite relationship in the pathogenesis of hepatocellular carcinoma. International journal of cancer 27 28205209
2014 The effect of CXCL9 on the invasion ability of hepatocellular carcinoma through up-regulation of PREX2. Journal of molecular histology 26 25151370
2019 Somatic mutations of PREX2 gene in patients with hepatocellular carcinoma. Scientific reports 20 30796242
2019 Involvement of TLR4/ CXCL9/ PREX-2 pathway in the development of hepatocellular carcinoma (HCC) and the promising role of early administration of lactobacillus plantarum in Wistar rats. Tissue & cell 20 31582017
2017 Replication Study: Melanoma genome sequencing reveals frequent PREX2 mutations. eLife 19 28100394
2015 p21-activated Kinases (PAKs) Mediate the Phosphorylation of PREX2 Protein to Initiate Feedback Inhibition of Rac1 GTPase. The Journal of biological chemistry 19 26438819
2016 Upregulation of PREX2 promotes the proliferation and migration of hepatocellular carcinoma cells via PTEN-AKT signaling. Oncology letters 15 26998152
2024 PREX2 contributes to radiation resistance by inhibiting radiotherapy-induced tumor immunogenicity via cGAS/STING/IFNs pathway in colorectal cancer. BMC medicine 14 38609982
2021 Structural analysis of the PTEN:P-Rex2 signaling complex reveals how cancer-associated mutations coordinate to hyperactivate Rac1. Science signaling 12 33947796
2016 PREX2 promotes the proliferation, invasion and migration of pancreatic cancer cells by modulating the PI3K signaling pathway. Oncology letters 10 27446408
2025 Targeting the PREX2/RAC1/PI3Kβ Signaling Axis Confers Sensitivity to Clinically Relevant Therapeutic Approaches in Melanoma. Cancer research 5 39636745
2018 Structural and biochemical characterization of the pleckstrin homology domain of the RhoGEF P-Rex2 and its regulation by PIP3. Journal of structural biology: X 5 34958187
2016 Mechanistic insights into the role of truncating PREX2 mutations in melanoma. Molecular & cellular oncology 5 27314100
2021 PREX2 gene's expression in gastric antral epithelial cells of patients with H. pylori infection. Arquivos de gastroenterologia 3 34705970
2014 Registered report: Melanoma genome sequencing reveals frequent PREX2 mutations. eLife 3 25490935
2013 P-Rex2, a Rac-guanine nucleotide exchange factor, is expressed selectively in ribbon synaptic terminals of the mouse retina. BMC neuroscience 3 23844743
2025 P-Rex2 suppresses glucose uptake into liver and skeletal muscle through different adaptor functions. Scientific reports 2 40764335
2022 P-Rex2 mediation of synaptic plasticity contributes to bone cancer pain. Molecular pain 2 35083941
2022 Sustainable and cost-effective ternary electrolyte Et3NHCl-AlCl3-Mg(DEP)2 for high-performance rechargeable magnesium batteries. Physical chemistry chemical physics : PCCP 1 34988572
2026 P-Rex2 exhibits unique structural features and regulatory mechanisms distinct from the closely related RhoGEF P-Rex1. bioRxiv : the preprint server for biology 0 41542420
2025 AHCYL1 mediates the tumor-promoting effect of PREX2 in non-small cell lung carcinoma. Theranostics 0 40365293
2025 Unraveling the role of PREX2 mutations as a biomarker for immunotherapy response in colorectal cancer. Cancer biomarkers : section A of Disease markers 0 40971540
2021 PREX2 promotes the proliferation, invasion and migration of pancreatic cancer cells by modulating the PI3K signaling pathway. Oncology letters 0 34386078