Hillig R C, Renault L, Vetter I R, Drell T, Wittinghofer A, Becker J
Max-Planck-Institut für molekulare Physiologie, Abteilung Strukturelle Biologie, Dortmund, Germany.
Mol Cell. 1999 Jun;3(6):781-91. doi: 10.1016/s1097-2765(01)80010-1.
rna1p is the Schizosaccharomyces pombe ortholog of the mammalian GTPase-activating protein (GAP) of Ran. Both proteins are essential for nuclear transport. Here, we report the crystal structure of rna1p at 2.66 A resolution. It contains 11 leucine-rich repeats that adopt the nonglobular shape of a crescent, bearing no resemblance to RhoGAP or RasGAP. The invariant residues of RanGAP form a contiguous surface, strongly indicating the Ran-binding interface. Alanine mutations identify Arg-74 as a critical residue for GTP hydrolysis. In contrast to RasGAP and RhoGAP, Arg-74 could be substituted by lysine and contributed significantly to the binding of Ran. Therefore, we suggest a GAP mechanism for rna1p, which constitutes a variation of the arginine finger mechanism found for Ras GAP and RhoGAP.
Rna1p是粟酒裂殖酵母中与哺乳动物Ran的GTP酶激活蛋白（GAP）相对应的同源物。这两种蛋白质对于核运输都是必不可少的。在此，我们报告了Rna1p在2.66埃分辨率下的晶体结构。它包含11个富含亮氨酸的重复序列，呈新月形的非球状形状，与RhoGAP或RasGAP没有相似之处。RanGAP的不变残基形成一个连续的表面，强烈表明Ran结合界面。丙氨酸突变确定Arg-74是GTP水解的关键残基。与RasGAP和RhoGAP不同，Arg-74可以被赖氨酸取代，并对Ran的结合有显著贡献。因此，我们提出了Rna1p的GAP机制，它构成了Ras GAP和RhoGAP中发现的精氨酸指机制的一种变体。
