Veeraragavan K, Coulombe R, Gagnon C
Urology Research Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada.
Biochem Biophys Res Commun. 1988 Apr 29;152(2):732-8. doi: 10.1016/s0006-291x(88)80099-8.
The secretory proteins from adrenal chromaffin granules, chromogranins A, A1 and A2, were found to be excellent in vitro methyl acceptor proteins. The purified protein-carboxyl methylase (PCM) from bovine erythrocytes incorporated 660, 2540 and 7890 pmol of methyl group/10 min/mg protein in chromogranins A, A1 and A2, respectively. However, dopamine beta-hydroxylase, another secretory protein within chromaffin granules was poorly methylated. The stoichiometry of methylation for chromogranins A, A1 and A2 was 0.26, 0.89 and 1.3 mol of methyl group/mol of protein, respectively. Kinetic analysis showed that chromogranins A1 had the highest turnover rate followed by chromogranins A2 and A. These chromogranins are the first secretory proteins to be stoichiometrically methylated in vitro without prior deamidation.
肾上腺嗜铬粒蛋白中的分泌蛋白，嗜铬粒蛋白A、A1和A2，被发现是优秀的体外甲基受体蛋白。从牛红细胞中纯化的蛋白羧基甲基转移酶（PCM）分别在嗜铬粒蛋白A、A1和A2中以660、2540和7890皮摩尔甲基/10分钟/毫克蛋白的速度掺入甲基。然而，嗜铬粒蛋白中的另一种分泌蛋白多巴胺β-羟化酶甲基化程度很低。嗜铬粒蛋白A、A1和A2的甲基化化学计量比分别为0.26、0.89和1.3摩尔甲基/摩尔蛋白。动力学分析表明，嗜铬粒蛋白A1的周转速率最高，其次是嗜铬粒蛋白A2和A。这些嗜铬粒蛋白是首批在体外无需预先脱酰胺就进行化学计量甲基化的分泌蛋白。
