This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| PIK3R1 | |
|---|---|
| Name | PIK3R1 |
| Organism | Homo sapiens |
| Uniprot | P85A_HUMAN |
PIK3R1 is the gene encoding the regulatory subunit p85α of class IA phosphoinositide 3-kinase, a central adaptor in receptor-proximal signaling networks. The protein scaffolds interactions that couple receptor tyrosine kinases and adaptor proteins to catalytic subunits, influencing cell growth, survival, and metabolism. PIK3R1 participates in pathways implicated in development and disease across systems studied by investigators at institutions like Harvard University, Massachusetts Institute of Technology, and National Institutes of Health.
PIK3R1 acts as a regulatory scaffold binding catalytic subunits and phosphotyrosine motifs from receptors such as Epidermal growth factor receptor, Insulin receptor, Vascular endothelial growth factor receptor, and adaptors like GRB2, IRS1, Shc1, and Gab1. The p85α subunit stabilizes catalytic p110 isoforms and modulates lipid kinase activity that generates phosphatidylinositol (3,4,5)-trisphosphate, recruiting effectors including AKT1, PDK1, and mTOR, thereby linking extracellular cues from ligands like Epidermal growth factor and Insulin to intracellular programs governed by nodes studied in work from Stanford University and Cold Spring Harbor Laboratory.
PIK3R1 encodes domains including an N-terminal SH3 domain, a Rho-GAP–like domain, and two SH2 domains (nSH2 and cSH2) separated by an inter-SH2 (iSH2) region that binds p110 catalytic subunits such as PIK3CA and PIK3CB. The modular architecture permits interactions with phosphotyrosine motifs on receptors like Platelet-derived growth factor receptor and adaptors such as CRKL, while the iSH2 stabilizes heterodimer formation observed in structural studies by groups at European Molecular Biology Laboratory and Max Planck Society.
PIK3R1-mediated complexes are regulated by phosphorylation events catalyzed by kinases including SRC family kinases, JAK2, and Casein kinase II, and by phosphatases such as PTEN and PP2A. Downstream signaling intersects with pathways centered on AKT1, mTORC1, FOXO transcription factors, and regulators implicated in cell cycle control like Cyclin D1 and TP53, integrating signals from cytokine receptors such as Interleukin-6 receptor and growth factor systems studied in models like Drosophila melanogaster and Mus musculus.
Alterations affecting PIK3R1 function are associated with disorders including insulin resistance, immunodeficiency, and cancer. Loss-of-function variants contribute to primary immunodeficiency syndromes characterized in cohorts at Great Ormond Street Hospital and Mayo Clinic, while somatic alterations correlate with tumor types investigated at cancer centers such as Memorial Sloan Kettering Cancer Center and Dana-Farber Cancer Institute. PIK3R1 interactions influence sensitivity to targeted agents like PI3K inhibitors, mTOR inhibitors, and combinations evaluated in trials by National Cancer Institute and pharmaceutical companies including Novartis and AstraZeneca.
Recurrent somatic mutations and splice-site alterations in PIK3R1 have been reported in studies from consortia like The Cancer Genome Atlas and projects at Wellcome Sanger Institute, with hotspots clustering in the iSH2 and nSH2 regions that perturb p110 binding and catalytic regulation. Germline variants underlie syndromes reviewed in literature from American College of Medical Genetics and Genomics and clinical series at Johns Hopkins Hospital, producing phenotypes ranging from growth abnormalities to immune dysregulation; genotype–phenotype correlations are the subject of investigations at European Society for Immunodeficiencies and translational programs at UCL Great Ormond Street Institute of Child Health.
PIK3R1 function has been interrogated using genetically engineered mice, CRISPR/Cas9-edited cell lines, and patient-derived xenografts established by groups at The Jackson Laboratory and academic cores at Broad Institute. Structural insights derive from X-ray crystallography and cryo-EM studies performed at facilities like Diamond Light Source and European Synchrotron Radiation Facility, while interactome mapping uses proteomics platforms developed at Proteome Research Center and bioinformatics resources including Ensembl and Gene Ontology-linked databases used by researchers at European Bioinformatics Institute.
Category:Human proteins