Structure, function and regulation of the coated vesicle V-ATPase.
The coated vesicle V-ATPase plays an important role in both receptor-mediated endocytosis and intracellular membrane traffic by providing the acidic environment required for ligand-receptor dissociation and receptor recycling. The coated vesicle V-ATPase is a macromolecular complex of relative molecular mass 750,000 composed of nine subunits arranged in two structural domains. The peripheral V1 domain, which has a relative molecular mass of 500,000, has the subunit structure 73(3)58(3)40(1)34(1)33(1) and possesses all the nucleotide binding sites of the V-ATPase. The integral Vo domain of relative molecular mass 250,000 has a subunit composition of 100(1)38(1)19(1)17(6) and possesses the pathway for proton conduction across the membrane. Reassembly studies have allowed us to probe the role of specific subunits in the V-ATPase complex while chemical labeling studies have allowed us to identify specific residues which play a critical role in catalysis. From both structural analysis and sequence homology, the vacuolar-type H(+)-ATPases resemble the F-type H(+)-ATPases. Unlike the F1 and Fo domains of the F-type ATPases, however, the V1 and Vo domains do not appear to function independently. The possible relevance of these observations to the regulation of vacuolar acidification is discussed.
Forgac
M
M
Department of Cellular and Molecular Physiology, Tufts University School of Medicine, Boston, MA 02111.
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000502:physiology; D000818:Animals; D001665:Binding Sites; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D015388:Organelles / Q000201:enzymology; D011487:Protein Conformation; D025262:Vacuolar Proton-Translocating ATPases
D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases