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: Motility/polarity/chemotaxis; Kinase, lipid; Enzyme, regulatory subunit
Molecular Function: protein C-terminus binding; protein domain specific binding; neurotrophin TRKA receptor binding; 1-phosphatidylinositol-3-kinase activity; platelet-derived growth factor receptor binding; phosphoprotein binding; 1-phosphatidylinositol-3-kinase regulator activity; phosphoinositide 3-kinase regulator activity; receptor tyrosine kinase binding; protein kinase binding; protein phosphatase 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; kinase activity; 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; positive regulation of apoptosis; response to glucocorticoid stimulus; signal transduction; regulation of phosphoinositide 3-kinase activity; protein amino acid phosphorylation; NFAT protein import into nucleus; response to insulin stimulus; negative regulation of blood pressure; negative regulation of proteolysis; glucose metabolic process; negative regulation of cell-matrix adhesion; positive regulation of myoblast differentiation; insulin-like growth factor receptor signaling pathway; B cell differentiation; insulin receptor signaling pathway; positive regulation of transcription from RNA polymerase II promoter; positive regulation of protein amino acid phosphorylation; negative regulation of cell-cell adhesion; 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.