Identified as a tyrosine phosphorylated protein in Rous sarcoma virus- transformed chick embryo fibroblasts (CEF), caveolin is now known to be ubiquitously expressed. Caveolin (also known as VIP21) localizes to non-clathrin membrane invaginations (caveolae) on the inner surface of the plasma membrane. This transmembrane protein plays a structural role in these specializations. Caveolin is also present at the trans-Golgi network (TGN) and similar quantities are found in apically and basolaterally destined transport vesicles. Caveolin is part of a complex containing glycosylphosphatidylinositol (GPI)-linked molecules and cytoplasmic signaling proteins. Caveolin is a transmembrane adaptor molecule that can simultaneously recognize GPI-linked proteins and interact with downstream cytoplasmic signaling molecules, such as c-yes, Annexin II, and hetero-trimeric G proteins. Although caveolin 2 is similar to caveolin 1 in distribution and tissue expression, caveolin 2 is most abundant in adipose tissue and its expression is up-regulated upon differentiation. This antibody has been reported to recognize an epitope located within region 79-88 of caveolin 2.