PIK3R1: regulatory subunit of phosphoinositide-3-kinase. Mediates binding to a subset of tyrosine-phosphorylated proteins through its SH2 domain. Acts as an adapter, mediating the association of the p110 catalytic unit of the alpha, beta and delta enzymes to the plasma membrane, where p110 phosphorylates inositol lipids. May play an additional role in the regulation of the actin cytoskeleton. Necessary for the insulin-stimulated increase in glucose uptake and glycogen synthesis in insulin-sensitive tissues. Its SH2 domains interacts with the YTHM motif of phosphorylated INSR in vitro. Defects in PIK3R1 are a cause of severe insulin resistance. Four alternatively spliced isoforms have been described.
Protein type: Motility/polarity/chemotaxis; Enzyme, regulatory subunit; Kinase, lipid
Chromosomal Location of Human Ortholog: 5q13.1
Cellular Component: membrane; cytoplasm; plasma membrane; intercellular junction; cytosol; nucleus; phosphoinositide 3-kinase complex
Molecular Function: insulin binding; insulin-like growth factor receptor binding; protein binding; ErbB-3 class receptor binding; neurotrophin TRKA receptor binding; insulin receptor substrate binding; phosphoinositide 3-kinase binding; phosphoinositide 3-kinase regulator activity; transmembrane receptor protein tyrosine kinase adaptor protein activity; protein phosphatase binding; transcription factor binding; insulin receptor binding
Biological Process: negative regulation of osteoclast differentiation; phosphoinositide 3-kinase cascade; viral reproduction; nerve growth factor receptor signaling pathway; positive regulation of RNA splicing; regulation of phosphoinositide 3-kinase activity; T cell receptor signaling pathway; NFAT protein import into nucleus; protein amino acid phosphorylation; positive regulation of glucose import; phosphoinositide phosphorylation; phospholipid metabolic process; positive regulation of transcription factor import into nucleus; epidermal growth factor receptor signaling pathway; platelet activation; phosphoinositide-mediated signaling; fibroblast growth factor receptor signaling pathway; protein stabilization; negative regulation of cell-matrix adhesion; positive regulation of tumor necrosis factor production; DNA damage response, signal transduction resulting in induction of apoptosis; insulin-like growth factor receptor signaling pathway; induction of apoptosis via death domain receptors; cellular response to insulin stimulus; B cell differentiation; T cell costimulation; phosphatidylinositol biosynthetic process; insulin receptor signaling pathway; innate immune response; cell glucose homeostasis; positive regulation of transcription from RNA polymerase II promoter; blood coagulation; vascular endothelial growth factor receptor signaling pathway; leukocyte migration; negative regulation of apoptosis; positive regulation of cell migration
Disease: Agammaglobulinemia 7, Autosomal Recessive; Short Syndrome; Immunodeficiency 36
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