title: Primary structure and biochemical characterization of yeast GTPase-activating proteins with substrate preference for the transport GTPase Ypt7p.
abstract: Small GTPases of the Ypt/Rab family are regulators of vesicular protein trafficking in exo-and endocytosis. GTPase-activating proteins (GAP) play an important role as down regulators of GTPases. We here report the molecular cloning of a novel GAP-encoding gene (GYP7, for GAP for Ypt7) by high expression from a Saccharomyces cerevisiae genomic library. The GYP7 gene encodes a hydrophilic protein with a molecular mass of 87 kDa. Comparison of its primary sequence with that of the three other known GAPs for transport GTPases, the yeast Gyp6 and Gyp1 proteins and the Rab3A-GAP from rat brain, shows similarity between the yeast GAPs only. Like GYP6 and GYP1, GYP7 is not essential for yeast cell viability. Gyp7p was able to most effectively accelerate the intrinsic GTPase activity of Ypt7p. It was also active, but to a lesser extent, on Ypt31p, Ypt32p and Ypt1p. Ypt6p, Sec4p and the human H-Ras protein did not serve as substrates. We also report the identification and cloning of a gene from the dimorphic yeast Yarrowia lipolytica that encodes a protein whose primary structure and biochemical activity are significantly related to those of Gyp7p from baker's yeast.
authors: Max-Planck-Institute for Biophysical Chemistry, Department of Molecular Genetics, Göttingen, Germany.
authors: P
authors: P
authors: Vollmer
authors: E
authors: E
authors: Will
authors: D
authors: D
authors: Scheglmann
authors: M
authors: M
authors: Strom
authors: D
authors: D
authors: Gallwitz
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D005800:Genes, Fungal / Q000235:genetics; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D013379:Substrate Specificity; D020691:rab GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins
chemical_list: D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D020703:ras GTPase-Activating Proteins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins