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: Enzyme, regulatory subunit; Kinase, lipid; Motility/polarity/chemotaxis
Molecular Function: protein C-terminus binding; protein domain specific binding; 1-phosphatidylinositol-3-kinase activity; neurotrophin TRKA receptor binding; platelet-derived growth factor receptor binding; phosphoprotein binding; phosphoinositide 3-kinase regulator activity; 1-phosphatidylinositol-3-kinase regulator activity; receptor tyrosine kinase binding; protein phosphatase binding; transcription factor binding; protein kinase binding; insulin receptor binding; ATPase binding; calmodulin binding; insulin binding; insulin-like growth factor receptor binding; protein binding; ErbB-3 class receptor binding; insulin receptor substrate binding; ubiquitin protein ligase binding; phosphoinositide 3-kinase binding; estrogen receptor binding; receptor binding
Biological Process: negative regulation of osteoclast differentiation; phosphoinositide 3-kinase cascade; negative regulation of heart rate; response to cAMP; negative regulation of smooth muscle cell proliferation; response to glucocorticoid stimulus; signal transduction; positive regulation of RNA splicing; NFAT protein import into nucleus; regulation of phosphoinositide 3-kinase activity; protein amino acid phosphorylation; response to insulin stimulus; phosphoinositide phosphorylation; positive regulation of transcription factor import into nucleus; negative regulation of blood pressure; negative regulation of proteolysis; protein stabilization; glucose metabolic process; negative regulation of cell-matrix adhesion; positive regulation of tumor necrosis factor production; positive regulation of myoblast differentiation; cellular response to insulin stimulus; insulin-like growth factor receptor signaling pathway; induction of apoptosis via death domain receptors; DNA damage response, signal transduction resulting in induction of apoptosis; B cell differentiation; insulin receptor signaling pathway; cell glucose homeostasis; positive regulation of transcription from RNA polymerase II promoter; negative regulation of cell-cell adhesion; positive regulation of protein amino acid phosphorylation; positive regulation of cell migration; negative regulation of apoptosis
SS: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.