Schatzman R C, Grifo J A, Merrick W C, Kuo J F
FEBS Lett. 1983 Aug 8;159(1-2):167-70. doi: 10.1016/0014-5793(83)80439-6.
The ability of homogeneous phospholipid-sensitive Ca2+-dependent protein kinase (PL-Ca-PK) from pig spleen to phosphorylate eukaryotic initiation factor 2 (eIF-2) was examined. PL-Ca-PK phosphorylated the beta-subunit of eIF-2, whereas myosin light chain kinase (MLCK) and cyclic AMP- and cyclic GMP-dependent protein kinases (cA-PK and cG-PK) did not. PL-Ca-PK could incorporate a maximum of 1.6 mol phosphate/mol eIF-2. The app. Km and Vmax for PL-Ca-PK phosphorylation of eIF-2 were 0.13 microM and 0.02 mumol.min-1.mg enzyme-1, respectively. Phosphoamino acid analysis revealed that incorporation of phosphate into eIF-2 occurred almost exclusively at serine residues. These findings indicate that eIF-2 was an effective substrate for PL-Ca-PK, suggesting that this enzyme may play a role in the regulation of protein synthesis.
对猪脾脏中同源磷脂敏感的钙依赖性蛋白激酶（PL-Ca-PK）磷酸化真核起始因子2（eIF-2）的能力进行了检测。PL-Ca-PK使eIF-2的β亚基磷酸化，而肌球蛋白轻链激酶（MLCK）以及环磷酸腺苷和环磷酸鸟苷依赖性蛋白激酶（cA-PK和cG-PK）则不能。PL-Ca-PK最多可将1.6摩尔磷酸/摩尔eIF-2掺入。PL-Ca-PK对eIF-2进行磷酸化的表观Km和Vmax分别为0.13微摩尔和0.02微摩尔·分钟-1·毫克酶-1。磷酸氨基酸分析表明，磷酸掺入eIF-2几乎只发生在丝氨酸残基上。这些发现表明eIF-2是PL-Ca-PK的有效底物，提示该酶可能在蛋白质合成的调控中发挥作用。
