Sieghart W
J Neurochem. 1981 Nov;37(5):1116-24. doi: 10.1111/j.1471-4159.1981.tb04661.x.
Incubation of P2 fractions from rat cerebral cortex with 32Pi in the presence of L-glutamate caused an increased phosphorylation of a protein with apparent molecular weight of 43,000 (P43) as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. This glutamate-stimulated phosphorylation of P43 was already detectable 10 s after the addition of glutamate and was dependent on the concentrations of glutamate in the incubation medium. Other excitatory amino acids such as D-glutamate, L-aspartate, D,L-cysteic acid, L-cysteinesulfinic acid, and D,L-alpha-aminoadipic acid did not stimulate the phosphorylation of P43. In contrast, alpha-ketoglutarate and succinate stimulated the phosphorylation of this protein. Glutamate-stimulated phosphorylation of P43 seemed not to be mediated by either cAMP or cGMP and was inhibited by the presence of Ca2+ in the incubation medium. Experiments performed with metabolic inhibitors indicated that glutamate-stimulated protein phosphorylation is localized in mitochondria. This conclusion is supported by the occurrence of glutamate-stimulated phosphorylation of P43 in mitochondrial fractions from several peripheral tissues. The present results are consistent with the hypothesis that P43 is a component of the pyruvate dehydrogenase complex of mitochondria.
在L-谷氨酸存在的情况下，用32Pi孵育大鼠大脑皮层的P2级分，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和放射自显影法显示，一种表观分子量为43,000的蛋白质（P43）的磷酸化增加。添加谷氨酸后10秒即可检测到这种由谷氨酸刺激的P43磷酸化，并且它取决于孵育培养基中谷氨酸的浓度。其他兴奋性氨基酸，如D-谷氨酸、L-天冬氨酸、D,L-半胱氨酸、L-半胱亚磺酸和D,L-α-氨基己二酸，均未刺激P43的磷酸化。相反，α-酮戊二酸和琥珀酸刺激了该蛋白质的磷酸化。谷氨酸刺激的P43磷酸化似乎不是由cAMP或cGMP介导的，并且在孵育培养基中存在Ca2+时受到抑制。用代谢抑制剂进行的实验表明，谷氨酸刺激的蛋白质磷酸化定位于线粒体中。来自几种外周组织的线粒体级分中存在谷氨酸刺激的P43磷酸化，这一结果支持了这一结论。目前的结果与P43是线粒体丙酮酸脱氢酶复合体的一个组成部分这一假设一致。
