Zor T, Andorn R, Sofer I, Chorev M, Selinger Z
Department of Biological Chemistry and the Kuhne Minerva Center for Studies of Visual Transduction, The Hebrew University of Jerusalem, Israel.
FEBS Lett. 1998 Aug 21;433(3):326-30. doi: 10.1016/s0014-5793(98)00930-2.
Hydrolysis of GTP, bound to members of the G-protein superfamily, terminates their downstream signaling activity. A conserved glutamine serves a critical role in this pivotal guanosine triphosphatase (GTPase) reaction. However, the role of the catalytic glutamine in GTP hydrolysis is still not well understood. We have employed substrate-assisted catalysis to probe the catalytic mechanism of Gs alpha using GTP analogues. These GTP analogues, each having different functional groups, were designed to support or refute particular putative GTPase mechanisms. We have found that a hydrogen donor group, in close proximity to the gamma-phosphate of GTP, is necessary and sufficient to substitute for the function of the catalytic glutamine in the GTPase reaction.
与G蛋白超家族成员结合的GTP水解会终止其下游信号传导活性。一个保守的谷氨酰胺在这个关键的鸟苷三磷酸酶（GTPase）反应中起关键作用。然而，催化性谷氨酰胺在GTP水解中的作用仍未得到充分理解。我们利用底物辅助催化，使用GTP类似物来探究Gsα的催化机制。这些具有不同官能团的GTP类似物旨在支持或反驳特定的假定GTPase机制。我们发现，一个靠近GTPγ-磷酸基团的氢供体基团对于替代GTPase反应中催化性谷氨酰胺的功能是必要且充分的。
