CLONING AND CHARACTERIZATION OF 7 NOVEL DICTYOSTELIUM-DISCOIDEUM RAC-RELATED GENES BELONGING TO THE RHO-FAMILY OF GTPASES
CLONING AND CHARACTERIZATION OF 7 NOVEL DICTYOSTELIUM-DISCOIDEUM RAC-RELATED GENES BELONGING TO THE RHO-FAMILY OF GTPASES
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DOI：
10.1016/0378-1119(93)90448-c
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发表时间：
1993-12-22
期刊：
影响因子：
3.5
通讯作者：
CARDELLI, J
中科院分区：
文献类型：
--
作者：
BUSH, J;FRANEK, K;CARDELLI, J
细胞过程包括增殖、肌动蛋白细胞骨架的组织、囊泡运输和包含溶酶体/内体系统的蛋白质的分泌由Ras超家族的低分子量GTP结合蛋白调节。然而，到目前为止，只有三个Dictyosteelium discoideum ms-样基因和两个ypt-1/sec 4-样基因已被确定和表征。我们在这里报告的鉴定（使用寡脱氧核苷酸探针）的7个额外的cDNA编码的成员高度相关的Rac蛋白（Ras相关的C3肉毒杆菌毒素底物）属于Rho（Ras同源）家庭的GTP酶。这些rac相关基因中的三个（rac 1A、rac 1B和rac 1C）预测彼此具有> 90%氨基酸（aa）序列同一性并且与人rad基因产物具有> 80%同一性的蛋白质，而其他成员（racA、racB、racC和racD）预测与mel和rhoA基因产物以及彼此具有46-74%同一性的蛋白质。地方discoideum蛋白在已知对GTP结合重要的四个区域上是完全保守的，并且都含有由其他Rho蛋白共享的C-末端CAAX aa基序。有趣的是，D。discoideum rac相关基因在生长和发育过程中显示出独特的表达模式。例如，由三个高度相关的基因编码的rac 1 mRNA的稳态水平在聚集过程中短暂增加，然后迅速下降。相比之下，由其他rac样基因编码的mRNA的细胞丰度在发育期间从生长期间观察到的峰值水平以不同的速率下降到不同的水平。这表明这些基因编码的GTP结合蛋白在D.盘状花序生活史这项研究形成了未来调查的基础，以确定这些小GTP酶在细胞增殖，肌动蛋白细胞骨架的组织，囊泡运输在生长和发育过程中的作用，和溶酶体水解酶的分泌。
Cellular processes including proliferation, organization of the actin cytoskeleton, vesicular traffic and secretion of proteins comprising the lysosomal/endosomal system are regulated by low-molecular-weight GTP-binding proteins of the Ras superfamily. However, to date only three Dictyostelium discoideum ms-like genes and two ypt-1/sec4-like genes have been identified and characterized. We report here the identification (using an oligodeoxyribonucleotide probe) of seven additional cDNAs coding for members highly related to the Rac proteins (Ras-related-C3 botulinum toxin substrate) which belong to the Rho (Ras homologous) family of GTPases. Three of these rac-related genes (rac1A, rac1B and rac1C) predict proteins with > 90% amino acid (aa) sequence identity with each other and > 80% identity to the human rad gene product, whereas the other members (racA, racB, racC and racD) predict proteins with 46-74% identity to the mel and rhoA gene products and to each other. The D. discoideum proteins were entirely conserved over the four regions known to be important for GTP binding and all contained the C-terminal CAAX aa motifs shared by other Rho proteins. Interestingly, the D. discoideum rac-related genes revealed unique patterns of expression during growth and development. For instance, the steady-state level of rac1 mRNA, encoded by three highly related genes, increased transiently during aggregation and then rapidly decreased. In contrast, the cellular abundance of mRNAs encoded by the other rac-like genes decreased at different rates and to different levels during development from the peak levels observed during growth. This suggests that the GTP-binding proteins encoded by these genes may play unique roles during the different stages of the D. discoideum life cycle. This study forms the foundation of future investigations to determine the role of these small GTPases in cell proliferation, organization of the actin cytoskeleton, vesicular trafficking during growth and development, and secretion of lysosomal hydrolases.