May act as a scaffolding protein within caveolar membranes. Interacts directly with G-protein alpha subunits and can functionally regulate their activity. Acts as an accessory protein in conjunction with CAV1 in targeting to lipid rafts and driving caveolae formation. Positive regulator of cellular mitogenesis of the MAPK signaling pathway. Required for the insulin-stimulated nuclear translocation and activation of MAPK1 and STAT3, and the subsequent regulation of cell cycle progression (By similarity). Monomer or homodimer. Interacts with CAV1; the interaction forms a stable heterooligomeric complex that is required for targeting to lipid rafts and for caveolae formation. Tyrosine phosphorylated forms do not form heterooligomers with the Tyr-19-phosphorylated form existing as a monomer or dimer. Interacts (tyrosine phosphorylated form) with the SH2 domain-containing proteins, RASA1, NCK1 and SRC. Interacts (tyrosine phosphorylated form) with INSR. Interacts (Tyr-19 phosphorylated form) with MAPK1 (phosphorylated form); the interaction, promoted by insulin, leads to nuclear location and MAPK1 activation. Interacts with STAT3; the interaction is increased on insulin-induced tyrosine phosphorylation leading to STAT activation (By similarity). Potential hairpin-like structure in the membrane. Membrane protein of caveolae. Tyr-19-phosphorylated form is enriched at sites of cell-cell contact and is translocated to the nucleus in complex with MAPK1 in response to insulin. CAV1-mediated Ser-23-phosphorylated form locates to the plasma membrane (By similarity). Phosphorylated on serine and tyrosine residues. CAV1 promotes phosphorylation on Ser-23 which then targets the complex to the plasma membrane, lipid rafts and caveolae. Phosphorylation on Tyr-19 is required for insulin-induced phosphorylation of MAPK1 and DNA binding of STAT3. Tyrosine phosphorylation is induced by both EGF and insulin (By similarity). Belongs to the caveolin family.