Inhibition of catalytic unit of adenylate cyclase and activation of GTPase of Ni protein by βγ‐subunits of GTP‐binding proteins

FEBS Letters

Asakawa, Takeo¹  Enomoto, Keiichi¹ 

[1] Department of Pharmacology, Saga Medical School, Saga 840-01, Japan

关键词: Adenylate cyclase Enzyme inhibition Niprotein GTPase ADP-ribosylation Islet-activating protein (Rat brain);   

DOI  :  10.1016/0014-5793(86)80650-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A protein factor which inhibited adenylate cyclase was purified to apparent homogeneity from rat brain and identified as the βγ-subunits of the GTP-binding regulatory proteins of adenylate cyclase. (i) The βγ-subunits (protein factor) inhibited the partially purified catalytic unit of adenylate cyclase in the presence of an activator, forskolin or the stimulative regulatory protein (N_s), to 60 and 40% of the control, respectively; inhibition of the catalytic unit in the presence of forskolin required no guanine nucleotides. (ii) The subunits enhanced the GTPase activity of the purified α-subunit of the inhibitory regulatory protein (N_iα) 3.8-fold, (iii) The subunits stimulated ADP-ribosylation of n_iα catalyzed by islet-activating protein (pertussis toxin). ADP-ribosylation had no effect on the GTPase activity of N_iα in the presence of the βγ-subunits. The results suggest that direct inhibition of the catalytic unit by the βγ-subunits liberated from N_i is essential for the receptor-mediated inhibition of adenylate cyclase.

【 授权许可】

Unknown