IDENTIFICATION, SEQUENCE, AND EXPRESSION OF CAVEOLIN-2 DEFINES A CAVEOLIN GENE FAMILY

Caveolin, a 21- to 24-kDa integral membrane protein, is a principal co mponent of caveolae membranes, Caveolin interacts directly with hetero trimeric guanine nucleotide binding proteins (G proteins) and can func tionally regulate their activity, Here, an approximate to 20-kDa caveo lin-related protein, caveolin-2, was identified through microsequencin g of adipocyte-derived caveolin-enriched membranes; caveolin was reter med caveolin-1, Caveolins 1 and 2 are similar in most respects. mRNAs for both caveolin-1 and caveolin-2 are most abundantly expressed in wh ite adipose tissue and are induced during adipocyte differentiation. C aveolin-2 colocalizes with caveolin-1, indicating that caveolin-2 also localizes to caveolae, However, caveolin-1 and caveolin-2 differ in t heir functional interactions with heterotrimeric G proteins, possibly explaining why caveolin-1 and -2 are coexpressed within a single cell.