ROLE OF GTP HYDROLYSIS IN FISSION OF CAVEOLAE DIRECTLY FROM PLASMA-MEMBRANES

Caveolae are specialized invaginated cell surface microdomains of unde fined function. A cell-free system that reconstituted fission of caveo lae from lung endothelial plasma membranes was developed. Addition of cytosol and the hydrolysis of guanosine triphosphate (GTP) induced cav eolar fission. The budded caveolae were isolated as vesicles rich in c aveolin and the sialoglycolipid G(M1) but not glycosylphosphatidylinos itol (GPI)-anchored proteins. These vesicles contained the molecular m achinery for endocytosis and transcytosis. In permeabilized endothelia l cells, GTP stimulated, whereas GTP gamma S prevented, caveolar buddi ng and endocytosis of the cholera toxin B chain to endosomes. Thus, ca veolae may bud to form discrete carrier vesicles that participate in m embrane trafficking.