Saito Y
Department of Pharmacology, National Defense Medical College.
Nihon Rinsho. 1998 Jul;56(7):1750-5.
Small GTPase ras and heterotrimeric G proteins composed of alpha, beta and gamma subunits are members of a superfamily of regulatory GTP hydrolases. They function as molecular switches which cycle between an inactive GDP-bound state and an active GTP-bound state, and are involved in regulatory biological processes from the outside of the cell to its interior. Binding of GTP triggers conformational changes in switch regions, which enable alpha subunit and ras to interact with effector molecules. Beta gamma dimers dissociated from alpha subunit are signaling molecules in their own rights. These G proteins activate various signal transduction pathways including activation of MAP kinases, phosphoinositide 3-kinases and small GTPases.
小GTP酶Ras以及由α、β和γ亚基组成的异源三聚体G蛋白是调节性GTP水解酶超家族的成员。它们作为分子开关，在无活性的GDP结合状态和活性的GTP结合状态之间循环，并参与从细胞外到细胞内的调节生物过程。GTP的结合触发开关区域的构象变化，使α亚基和Ras能够与效应分子相互作用。从α亚基解离的βγ二聚体本身就是信号分子。这些G蛋白激活各种信号转导途径，包括丝裂原活化蛋白激酶（MAP激酶）、磷酸肌醇3激酶和小GTP酶的激活。
