Plays an important role in caveolar biogenesis and morphology. Regulates caveolae morphology by inducing membrane curvature within caveolae (By similarity). Plays a role in caveola formation in a tissue-specific manner. Required for the formation of caveolae in the lung and fat endothelia but not in the heart endothelia. Negatively regulates the size or stability of CAVIN complexes in the lung endothelial cells (PubMed:23652019). May play a role in targeting PRKCA to caveolae (By similarity). Component of the CAVIN complex composed of CAVIN1, CAVIN2, CAVIN3 and CAVIN4 (PubMed:19546242). Binds to PRKCA in the presence of phosphatidylserine. Interacts with CAVIN4; this augments the transactivation of NPPA by CAVIN4 (By similarity). Interacts with CAVIN1 (PubMed:25588833, PubMed:19546242). Interacts with CAV3 (By similarity). Localizes in the caveolae in a caveolin-dependent manner. Heart, adipose tissue, lung and endothelial cells (at protein level). Highly expressed in kidney and expressed at lower levels in liver, spleen, thymus, stomach, intestine and uterus. Expression gradually increases during embryonic stages and reaches a maximum in neonates. Up-regulated in response to cardiac hypertrophy and in serum-starved but not in density-dependent growth-arrested NIH3T3 cells. Down-regulated within 6 hours after the addition of serum or epidermal growth factor to serum-starved cells. The leucine-zipper domain is essential for its localization in the caveolae. The N-terminus is blocked. Mice show loss of endothelial caveolae in lung and adipose tissue but no effect on the abundance of endothelial caveolae in the heart. Binds phosphatidylserine (PS) in a calcium-independent manner. PS-binding is inhibited by phosphotidic acid and phosphatidylinositol. Does not bind phosphatidylcholine (By similarity). Belongs to the CAVIN family.