Wes P D, Yu M, Montell C
Department of Biological Chemistry, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
EMBO J. 1996 Nov 1;15(21):5839-48.
Neuronal activity dramatically increases the concentration of cytosolic Ca2+, which then serves as a second messenger to direct diverse cellular responses. Calmodulin is a primary mediator of Ca2+ signals in the nervous system. In a screen for calmodulin-binding proteins, we identified RIC, a protein related to the Ras subfamily of small GTPases. In addition to the ability to bind calmodulin, a number of unique features distinguished RIC from other Ras-like GTPases, including the absence of a signal for prenylation and a distinct effector (G2) domain. Furthermore, we describe two human proteins, RIN and RIT, which were 71% and 66% identical to RIC respectively, shared related G2 domains with RIC, and lacked prenylation signals, suggesting that the RIC family is conserved from flies to humans. While Ric and RIT were widely expressed, expression of RIN was confined to the neuron system.
神经元活动会显著提高胞质Ca2+的浓度，随后Ca2+作为第二信使来指导多种细胞反应。钙调蛋白是神经系统中Ca2+信号的主要介导者。在一项针对钙调蛋白结合蛋白的筛选中，我们鉴定出RIC，一种与小GTP酶Ras亚家族相关的蛋白质。除了具有结合钙调蛋白的能力外，RIC还有许多独特特征，使其有别于其他类Ras GTP酶，包括缺乏异戊二烯化信号和一个独特的效应器（G2）结构域。此外，我们还描述了两种人类蛋白质RIN和RIT，它们分别与RIC有71%和66%的同源性，与RIC共享相关的G2结构域，并且缺乏异戊二烯化信号，这表明RIC家族从果蝇到人类都是保守的。虽然Ric和RIT广泛表达，但RIN的表达局限于神经系统。
