Modulates the morphology of formed caveolae in cardiomyocytes, but is not required for caveolar formation. Facilitates the recruitment of MAPK1/3 to caveolae within cardiomyocytes and regulates alpha-1 adrenergic receptor-induced hypertrophic responses in cardiomyocytes through MAPK1/3 activation (PubMed:24567387). Contributes to proper membrane localization and stabilization of caveolin-3 (CAV3) in cardiomyocytes (PubMed:26497963). Induces RHOA activation and activates NPPA transcription and myofibrillar organization through the Rho/ROCK signaling pathway (PubMed:18332105). Component of the CAVIN complex composed of CAVIN1, CAVIN2, CAVIN3 and CAVIN4. Interacts with CAVIN1 (PubMed:19546242). Interacts with CAVIN2; this augments the transactivation of NPPA. Interacts with CAV3, ADRA1A, ADRA1B, MAPK1 and MAPK3 (By similarity). In cardiomyocytes, accumulates in the Z-line of the sarcomere. In vascular smooth muscle cells, detected diffusely throughout the cytoplasm (PubMed:18332105). Localizes in the caveolae in a caveolin-dependent manner (PubMed:19546242). Abundantly expressed in cardiac and skeletal muscle (at protein level). Weaker expression in aorta and lung. In heart, expressed in cardiomyocytes and vascular smooth muscle cells but not in other surrounding cells including vascular endothelial cells. Expression increases during development from embryo to adult. Up-regulated in response to cardiac hypertrophy. The coiled coil domain (residues 44-77) is essential for membrane-targeting in cardiomyocytes. Mice exhibit normal caveolar morphology and cardiac function under physiological conditions, whereas upon alpha-1 adrenergic receptor stimulation, show attenuation of cardiac hypertrophy accompanied by suppressed MAPK1/2 activation. Belongs to the CAVIN family.