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. Note: This description may include information from UniProtKB.
Protein type: Kinase, lipid; Motility/polarity/chemotaxis
Molecular Function: 1-phosphatidylinositol-3-kinase activity; 1-phosphatidylinositol-3-kinase regulator activity; ATPase binding; calmodulin binding; ErbB-3 class receptor binding; estrogen receptor binding; insulin binding; insulin receptor binding; insulin receptor substrate binding; insulin-like growth factor receptor binding; neurotrophin TRKA receptor binding; phosphoinositide 3-kinase regulator activity; phosphoprotein binding; phosphotyrosine binding; platelet-derived growth factor receptor binding; protein binding; protein C-terminus binding; protein domain specific binding; protein heterodimerization activity; protein kinase binding; protein phosphatase binding; receptor binding; receptor tyrosine kinase binding; transcription factor binding; ubiquitin protein ligase binding
Biological Process: B cell differentiation; cell glucose homeostasis; cellular response to insulin stimulus; cellular response to UV; DNA damage response, signal transduction resulting in induction of apoptosis; glucose metabolic process; induction of apoptosis via death domain receptors; insulin receptor signaling pathway; insulin-like growth factor receptor signaling pathway; negative regulation of apoptosis; negative regulation of blood pressure; negative regulation of cell adhesion; negative regulation of cell-cell adhesion; negative regulation of cell-matrix adhesion; negative regulation of heart rate; negative regulation of muscle cell apoptotic process; negative regulation of osteoclast differentiation; negative regulation of proteolysis; negative regulation of smooth muscle cell proliferation; NFAT protein import into nucleus; phosphoinositide 3-kinase cascade; positive regulation of cell migration; positive regulation of endoplasmic reticulum unfolded protein response; positive regulation of gene expression; positive regulation of myoblast differentiation; positive regulation of protein phosphorylation; positive regulation of RNA splicing; positive regulation of transcription factor import into nucleus; positive regulation of transcription from RNA polymerase II promoter; positive regulation of tumor necrosis factor production; protein amino acid phosphorylation; protein stabilization; protein transport; regulation of insulin receptor signaling pathway; regulation of phosphoinositide 3-kinase activity; regulation of stress fiber assembly; response to cAMP; response to glucocorticoid stimulus; response to insulin stimulus; signal transduction; transport