Browning M D, Endo S, Smith G B, Dudek E M, Olsen R W
Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80222.
Neurochem Res. 1993 Jan;18(1):95-100. doi: 10.1007/BF00966927.
Previous work has shown that the GABAA-receptor (GABAA-R) could be phosphorylated by cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and a receptor associated kinase. However, no clear picture has yet emerged concerning the particular subunit/subtypes of the GABAA-R that were phosphorylated by PKA and PKC. In the present report we show that an antibody raised against a 23 amino acid polypeptide corresponding to a sequence in the putative intracellular loop of the beta 1 subunit of the receptor blocks the in vitro phosphorylation of the purified receptor by PKA and PKC. Moreover, N-terminal sequence analysis of the principal phosphopeptide fragment obtained after proteolysis of the receptor yielded a sequence that corresponds to the beta 3 subunit of the receptor. Such data provide additional support for our hypothesis (Browning et al., 1990, Proc. Natl. Acad. Sci. USA 87:1315-1317) that both PKA and PKC phosphorylate the beta-subunit of the GABAA-R.
先前的研究表明，γ-氨基丁酸A型受体（GABAA-R）可被环磷酸腺苷依赖性蛋白激酶（PKA）、蛋白激酶C（PKC）以及一种受体相关激酶磷酸化。然而，关于PKA和PKC所磷酸化的GABAA-R的特定亚基/亚型，目前尚无清晰的认识。在本报告中，我们表明，针对与受体β1亚基假定细胞内环中的一段序列相对应的23个氨基酸多肽产生的抗体，可阻断PKA和PKC对纯化受体的体外磷酸化。此外，对受体蛋白水解后获得的主要磷酸肽片段进行N端序列分析，得到了一个与受体β3亚基相对应的序列。这些数据为我们的假设（Browning等人，1990年，《美国国家科学院院刊》87:1315 - 1317）提供了更多支持，即PKA和PKC均可磷酸化GABAA-R的β亚基。
