Vollmer P, Will E, Scheglmann D, Strom M, Gallwitz D
Max-Planck-Institute for Biophysical Chemistry, Department of Molecular Genetics, Göttingen, Germany.
Eur J Biochem. 1999 Feb;260(1):284-90. doi: 10.1046/j.1432-1327.1999.00192.x.
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.
Ypt/Rab家族的小GTP酶是胞吐作用和胞吞作用中囊泡蛋白运输的调节因子。GTP酶激活蛋白（GAP）作为GTP酶的负调节因子发挥着重要作用。我们在此报告通过从酿酒酵母基因组文库中高表达克隆出一个新的GAP编码基因（GYP7，即Ypt7的GAP）。GYP7基因编码一种分子量为87 kDa的亲水性蛋白。将其一级序列与另外三种已知的运输GTP酶的GAP（酵母Gyp6和Gyp1蛋白以及大鼠脑内的Rab3A - GAP）的一级序列进行比较，发现仅酵母GAP之间存在相似性。与GYP6和GYP1一样，GYP7对酵母细胞活力并非必需。Gyp7p能够最有效地加速Ypt7p的内在GTP酶活性。它对Ypt31p、Ypt32p和Ypt1p也有活性，但程度较低。Ypt6p、Sec4p和人类H - Ras蛋白不作为底物。我们还报告了从双态酵母解脂耶氏酵母中鉴定和克隆出一个基因，该基因编码一种蛋白，其一级结构和生化活性与面包酵母的Gyp7p的一级结构和生化活性显著相关。
