An acylation cycle regulates localization and activity of palmitoylated Ras isoforms     

Rocks O  Peyker A  Kahms M  Verveer PJ  Koerner C  Lumbierres M  Kuhlmann J  Waldmann H  Wittinghofer A  Bastiaens PI 《Science (New York, N.Y.)》2005,307(5716):1746-1752

We show that the specific subcellular distribution of H- and Nras guanosine triphosphate-binding proteins is generated by a constitutive de/reacylation cycle that operates on palmitoylated proteins, driving their rapid exchange between the plasma membrane (PM) and the Golgi apparatus. Depalmitoylation redistributes farnesylated Ras in all membranes, followed by repalmitoylation and trapping of Ras at the Golgi, from where it is redirected to the PM via the secretory pathway. This continuous cycle prevents Ras from nonspecific residence on endomembranes, thereby maintaining the specific intracellular compartmentalization. The de/reacylation cycle also initiates Ras activation at the Golgi by transport of PM-localized Ras guanosine triphosphate. Different de/repalmitoylation kinetics account for isoform-specific activation responses to growth factors.  相似文献   

Structure of Rab GDP-dissociation inhibitor in complex with prenylated YPT1 GTPase     

Rak A  Pylypenko O  Durek T  Watzke A  Kushnir S  Brunsveld L  Waldmann H  Goody RS  Alexandrov K 《Science (New York, N.Y.)》2003,302(5645):646-650

Rab/Ypt guanosine triphosphatases (GTPases) represent a family of key membrane traffic regulators in eukaryotic cells whose function is governed by the guanosine diphosphate (GDP) dissociation inhibitor (RabGDI). Using a combination of chemical synthesis and protein engineering, we generated and crystallized the monoprenylated Ypt1:RabGDI complex. The structure of the complex was solved to 1.5 angstrom resolution and provides a structural basis for the ability of RabGDI to inhibit the release of nucleotide by Rab proteins. Isoprenoid binding requires a conformational change that opens a cavity in the hydrophobic core of its domain II. Analysis of the structure provides a molecular basis for understanding a RabGDI mutant that causes mental retardation in humans.  相似文献   

The Renin-Angiotensin System in the Bovine Utero-Placental Unit     

AH Nielsen  KH Schauser  H Winther  V Dantzer  K Poulsen 《Reproduction in domestic animals》2000,35(3-4):153-156

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铲式成穴器成穴性能的试验研究   总被引：4，自引：2，他引：2  

马成林  李成华  于海业  KH.Kromer 《农业机械学报》1999,30(2):33-37

根据铲式成穴器的成穴机理确定了其结构参数和工作参数的设计变化范围并按照二次回归试验设计方法进行了成穴器参数地成穴性能影响的试验,通过对试验结果垢统计分析,查明了成穴器参数对穴孔长度,穴孔宽度穴距和滑移系数的影响。  相似文献