title: Subunit H of the V-ATPase involved in endocytosis shows homology to beta-adaptins.
abstract: The vacuolar ATPase (V-ATPase) is a multisubunit enzyme that facilitates the acidification of intracellular compartments in eukaryotic cells and plays an important role in receptor-mediated endocytosis, intracellular trafficking processes, and protein degradation. In this study we show that the C-terminal fragment of 350 residues of the regulatory subunit H (V1H) of the V-ATPase shares structural and functional homologies with the beta-chains of adaptor protein complexes. Moreover, the fragment is similar to a region in the beta-subunit of COPI coatomer complexes, which suggests the existence of a shared domain in these three different families of proteins. For beta-adaptins, this fragment binds to cytoplasmic di-leucine-based sorting motifs such as in HIV-1 Nef that mediate endocytic trafficking. Expression of this fragment in cells blocks the internalization of transmembrane proteins, which depend on di-leucine-based motifs, whereas mutation of the consensus sequence GEY only partly diminishes the recognition of the sorting motif. Based on recent structural analysis, our results suggest that the di-leucine-binding domain consists of a HEAT or ARM repeat protein fold.
authors.affiliation: Howard Hughes Medical Institute, Department of Medicine, University of California at San Francisco, California 94143-0703, USA. geyer@mpimf-heidelberg.mpg.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Geyer
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Fackler
authors.forename: B Matija
authors.initials: BM
authors.lastname: Peterlin
mesh_terms: D033966:Adaptor Protein Complex beta Subunits / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004705:Endocytosis / Q000502:physiology*; D015693:Gene Products, nef / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D033966:Adaptor Protein Complex beta Subunits; D015693:Gene Products, nef; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C447617:VMA13 protein, S cerevisiae; D025262:Vacuolar Proton-Translocating ATPases