Caveolae are flask-shaped plasma membrane specializations. A 22-kDa protein, caveolin,
is a principal component of caveolar membranes in vivo. As recent evidence suggests that
caveolae may participate in G protein-coupled signaling events, we have investigated the
potential interaction of caveolin with heterotrimeric G proteins. Using cell fractionation
techniques, we found that mutational or pharmacologic activation of G sα prevents its
cofractionation with caveolin. In a second independent approach, we directly examined the …