Caveolae (also known as plasmalemmal vesicles) are 50-100 nm flask- shaped membranes that represent a subcompartment of the plasma membrane. On the basis of morphological studies, caveolae have been implicated to function in the transcytosis of various macromolecules (including LDL( across capillary endothelial cells, uptake of small molecules via potocytosis and the compartmentalization of certain signaling molecules including G protein-coupled receptors. Three proteins, caveolin-1, caveolin-2 and caveolin-3 have been identified as principle components of caveolae. Caveolin 1 (CAV1) is the main component of the caveolae plasma membranes found in most cell types. Caveolin 1 functions as a membrane adaptor to link integrin subunits to the tyrosine kinase FYN, an initiating step in coupling integrins to the Ras-ERK pathway and promoting cell cycle progression. CAV1 may also be a tumor suppressor gene and a negative regulator of the Ras-p42/44 MAP kinase cascade.Synonyms: CAV1