Gao P, Malbon C C
Department of Molecular Pharmacology, Diabetes and Metabolic Diseases Research Center, School of Medicine-HSC, State University of New York, Stony Brook, New York 11794-8651, USA.
J Biol Chem. 1996 Nov 29;271(48):30692-8. doi: 10.1074/jbc.271.48.30692.
Morphogen-induced decline in Gialpha triggers F9 teratocarcinoma stem cells to progress to primitive endoderm via activation of protein kinase C and mitogen-activated protein kinase (Gao, P., and Malbon, C. C. (1996) J. Biol. Chem. 271, 9002-9008). Constitutive expression of Gialpha2 blocks, whereas expression of Gsalpha provokes, progression to primitive endoderm, permitting identification of the effectors of the response-utilizing chimera created between Gialpha2 and Gsalpha. N-terminal substitution of Gsalpha with Gialpha2 sequence to create chimera Gialpha2 (1-54)/Gsalpha produced a chimera that activated adenylylcyclase but abolished progression to primitive endoderm and activation of phospholipase C. C-terminal substitution of Gsalpha with Gialpha2 sequence to Gsalpha/Gialpha2 (320-355) enhanced the ability of Gsalpha to promote progression. The Q205L-activated mutant of Gialpha2 suppresses, whereas the G225T-activated mutant of Gsalpha strongly activates phospholipase C and progression in these cells. The N-terminal region of Gsalpha (residues 62-86) appears to act as a dominant switch for the Gsalpha- (activation) versus Gialpha2- (suppression) mediated control of phospholipase C and progression to primitive endoderm.
形态发生素诱导的Gαi下降通过激活蛋白激酶C和丝裂原活化蛋白激酶，促使F9畸胎瘤干细胞向原始内胚层分化（高，P.，和马尔邦，C.C.（1996年）《生物化学杂志》271，9002 - 9008）。Gαi2的组成型表达会阻断，而Gsα的表达则会引发向原始内胚层的分化，这使得利用在Gαi2和Gsα之间构建的嵌合体来鉴定反应的效应器成为可能。用Gαi2序列对Gsα的N端进行取代以构建嵌合体Gαi2(1 - 54)/Gsα，产生了一种激活腺苷酸环化酶但消除了向原始内胚层分化和磷脂酶C激活的嵌合体。用Gαi2序列对Gsα的C端进行取代至Gsα/Gαi2(320 - 355)增强了Gsα促进分化的能力。Gαi2的Q205L激活突变体起抑制作用，而Gsα的G225T激活突变体则强烈激活这些细胞中的磷脂酶C并促进分化。Gsα的N端区域（第62 - 86位残基）似乎作为一个主导开关，用于控制Gsα介导的（激活）与Gαi2介导的（抑制）磷脂酶C以及向原始内胚层分化的过程。
