Lau Y S
Brain Res. 1984 Jul 30;307(1-2):181-9. doi: 10.1016/0006-8993(84)90472-4.
Calcium- and calmodulin-dependent protein kinase and phosphatase activities were studied in rat striatal particulate preparations. The effect of Ca2+ (0.1-0.5 mM) on phosphorylation was completely abolished in the preparation which had been washed 3 times with a buffer containing ethylene glycol bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA, 1.2 mM). Ca2+-stimulated phosphorylation was restored in a dose-dependent manner after calmodulin (1 microgram) was added to the assays. Ca2+ and calmodulin promoted the phosphate incorporation into two major striatal protein bands with estimated Mr at 52 and 40 kdaltons. The presence of phosphatase in the EGTA-pretreated preparations was negligible. Chronic treatment in rats with haloperidol (1 mg/kg, 20 days) produced a significant decrease in the Ca2+-independent phosphorylation but an increase in the extent of Ca2+ and calmodulin-dependent phosphorylation in the striatum. The chronic haloperidol treatment did not alter the striatal [125I]calmodulin binding curve. In vitro, haloperidol (even at 10(-4) M) had no effect on calmodulin-dependent phosphorylation. Haloperidol (10(-4) M) did not reduce the number but decreased the rate of [125I]calmodulin bindign to the striatal particulates. These data suggest that the link between dopamine receptors and calmodulin-dependent enzyme is dissociated in vitro. On the other hand, the potentiated sensitivity of calmodulin-dependent protein kinase in the chronic haloperidol-treated rats correlated with the supersensitive dopamine receptor responses occurred in these rats. Therefore, calmodulin-dependent protein kinase may biochemically regulate dopamine receptor functions in the striatum in vivo.
在大鼠纹状体微粒体制剂中研究了钙和钙调蛋白依赖性蛋白激酶及磷酸酶活性。在含乙二醇双（β-氨基乙基醚）-N，N'-四乙酸（EGTA，1.2 mM）的缓冲液中洗涤3次的制剂中，Ca2+（0.1 - 0.5 mM）对磷酸化的作用完全消失。在测定中加入钙调蛋白（1微克）后，Ca2+刺激的磷酸化以剂量依赖性方式恢复。Ca2+和钙调蛋白促进磷酸盐掺入两条主要的纹状体蛋白带，估计分子量分别为52和40千道尔顿。在EGTA预处理的制剂中磷酸酶的存在可忽略不计。用氟哌啶醇（1毫克/千克，20天）对大鼠进行慢性处理，导致纹状体中不依赖Ca2+的磷酸化显著降低，但依赖Ca2+和钙调蛋白的磷酸化程度增加。慢性氟哌啶醇处理未改变纹状体[125I]钙调蛋白结合曲线。在体外，氟哌啶醇（即使在10^(-4) M）对钙调蛋白依赖性磷酸化无影响。氟哌啶醇（10^(-4) M）不减少[125I]钙调蛋白与纹状体微粒结合的数量，但降低其结合速率。这些数据表明多巴胺受体与钙调蛋白依赖性酶之间的联系在体外被解离。另一方面，慢性氟哌啶醇处理的大鼠中钙调蛋白依赖性蛋白激酶的敏感性增强与这些大鼠中出现的多巴胺受体超敏反应相关。因此，钙调蛋白依赖性蛋白激酶可能在体内对纹状体中的多巴胺受体功能进行生化调节。
