Kojima M, Kitamura Y, Nomura Y, Sada H, Sperelakis N
Department of Pharmacology, School of Medicine, Yamaguchi University, Ube, Japan.
Jpn J Pharmacol. 1988 Sep;48(1):23-30. doi: 10.1254/jjp.48.23.
Developmental changes in the substrates for cholera toxin (CTX)- and pertussis toxin (PTX)-catalyzed ADP-ribosylation in cardiac (ventricular) cell membranes were studied in fetal (16- to 20-day), neonatal (0- to 20-day) and adult (2- to 3-month) rats. The CTX and PTX substrates were determined by the method of CTX-catalyzed and PTX-catalyzed ADP-ribosylation of the alpha-subunit of GTP-binding (G) proteins, respectively. As early as fetal day 16, three substrates (45-, 47- and 52-kDa proteins) were identified for CTX-catalyzed ADP-ribosylation and one substrate (41-kDa protein) for PTX-catalyzed ADP-ribosylation. The levels of the three CTX substrates (fmol/mg tissue) increased with development between fetal day 16 and neonatal day 16, and then they decreased to their adult levels. The level of the one PTX substrate (fmol/mg tissue) changed as follows: the substrate decreased between fetal day 16 and the day of birth, increased abruptly for 4 days neonatal and increased slowly thereafter until neonatal day 16, and then decreased to the final adult level. The PTX substrate seems to reach a nearly maximum level earlier than the CTX substrates. This information is essential for understanding the developmental changes in the transmembrane signaling system between membrane receptors and their effectors which are coupled with the stimulatory and inhibitory G proteins.
研究了胎龄16至20天的胎儿、0至20天的新生大鼠以及2至3个月大的成年大鼠心室细胞膜中霍乱毒素（CTX）和百日咳毒素（PTX）催化的ADP核糖基化底物的发育变化。CTX和PTX的底物分别通过GTP结合（G）蛋白α亚基的CTX催化和PTX催化的ADP核糖基化方法来确定。早在胎儿第16天，就鉴定出了三种CTX催化的ADP核糖基化底物（45、47和52 kDa蛋白）以及一种PTX催化的ADP核糖基化底物（41 kDa蛋白）。三种CTX底物的水平（fmol/mg组织）在胎儿第16天至新生第16天期间随着发育而增加，然后降至成年水平。单一PTX底物的水平（fmol/mg组织）变化如下：该底物在胎儿第16天至出生日之间减少，在新生期的4天内急剧增加，此后缓慢增加直至新生第16天，然后降至最终成年水平。PTX底物似乎比CTX底物更早达到几乎最高水平。这些信息对于理解膜受体与其效应器之间跨膜信号系统的发育变化至关重要，这些效应器与刺激性和抑制性G蛋白偶联。
