Joshi S A, Fan K P, Ho V W, Wong Y H
Department of Biology and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Kowloon, China.
FEBS Lett. 1998 Dec 11;441(1):67-70. doi: 10.1016/s0014-5793(98)01527-0.
Three widely-used Galpha(q) chimeras harboring the last five residues of Galpha(i), Galpha(o) and Galpha(z) (qi5, qo5 and qz5) were examined for their ability to serve as substrates for pertussis toxin (PTX)-catalyzed ADP-ribosylation. In COS-7 cells coexpressing one of the three opioid receptors (mu, delta, and kappa) and a Galpha(q) chimera, agonist-induced stimulation of phosphoinositide-specific phospholipase C (PI-PLC) was largely insensitive to PTX treatment. Only the qi5-mediated stimulation of PI-PLC by kappa-opioids was partially inhibited by PTX. In betagamma-release assays, PTX treatment did not affect the ability of opioid receptors to activate these chimeras. [32P]ADP-ribosylation labeled Galpha(i/o) but not qi5 or qo5, although the expression of these chimeras was confirmed by immunodetection. Thus, Galpha(q) chimeras with a Galpha(i/o)-like tail are insensitive to PTX treatment.
研究了三种广泛使用的携带Gα(i)、Gα(o)和Gα(z)最后五个残基的Gα(q)嵌合体（qi5、qo5和qz5）作为百日咳毒素（PTX）催化的ADP-核糖基化底物的能力。在共表达三种阿片受体（μ、δ和κ）之一和Gα(q)嵌合体的COS-7细胞中，激动剂诱导的磷酸肌醇特异性磷脂酶C（PI-PLC）刺激对PTX处理基本不敏感。只有κ-阿片类药物通过qi5介导的PI-PLC刺激被PTX部分抑制。在βγ释放试验中，PTX处理不影响阿片受体激活这些嵌合体的能力。[32P]ADP-核糖基化标记了Gα(i/o)，但未标记qi5或qo5，尽管这些嵌合体的表达通过免疫检测得到证实。因此，具有类似Gα(i/o)尾巴的Gα(q)嵌合体对PTX处理不敏感。
