PROTEIN PHOSPHATASE INHIBITOR PHOSPHORYLATION BY PROLINE DIRECTED PROTEIN KINASE

抑制剂-1(L-1)和DARPP-32，序列同源性在 氨基末端区域是蛋白质的内源调节器 磷酸酶-1(PP-1)。L-1在多种组织中都有表达， 而DARPP-32在大鼠的尾状核和纹状体中高度丰富。 哺乳动物的大脑。当每种蛋白质中的同源位置是 由cAMP依赖的蛋白激酶磷酸化，L-1和DARPP-32是 转化为PP-1的有效抑制剂。额外的磷酸化 DARPP-32中的位点可以调节DARPP-32的功能状态。 酪蛋白激酶II对Ser-102的磷酸化调节能力 DARPP-32作为cAMP依赖蛋白激酶的底物。 酪蛋白激酶I对Ser-137的磷酸化抑制作用 钙/钙调蛋白依赖的Thr-34去磷酸化 蛋白磷酸酶，钙调神经磷酸酶。因此，一条复杂的调控途径 对于PP-1活性的控制集中在单个分子上， DARPP-32，通过不同类别的DARPP-32多点磷酸化 蛋白激酶。正如上面对突触素II所描述的，我们最近 发现DARPP-32和L-1可以作为MAP的体外底物 激酶、cdc2和cdk5。我们希望能辨认出这些小说 磷酸化位点，决定了这些蛋白的功能效应 特异性磷酸化对磷酸酶的抑制作用，然后制备 针对这些部位的磷酸特异性抗体，以便研究 磷酸化状态的生理调节。

Inhibitor-1 (l-1) and DARPP-32, which share sequence homology in the amino-terminal region, are endogenous regulators of protein phosphatase-1 (PP-1). l-1 is expressed in a wide variety of tissues, while DARPP-32 is highly enriched in caudate nucleus and striatum in mammalian brain. When a homologous site in each protein is phosphorylated by cAMP-dependent protein kinase, l-1 and DARPP-32 are converted to potent inhibitors of PP-1. Additional phosphorylation sites in DARPP-32 can regulate the functional state of DARPP-32. Phosphorylation at Ser-102 by casein kinase II regulates the ability of DARPP-32 to serve as a substrate for cAMP-dependent protein kinase. Phosphorylation of Ser-137 by casein kinase I inhibits the dephosphorylation of Thr-34 by the calcium/calmodulin-dependent protein phosphatase, calcineurin. Thus, a complex regulatory pathway for the control of PP-1 activity converges on a single molecule, DARPP-32, by way of multi-site phosphorylation by distinct cla sses of protein kinase. As described above for synapsin II, we have recently found that DARPP-32 and l-1 can serve as in vitro substrates for MAP kinase, cdc2 kinase and cdk5. We wish to identify these novel phosphorylation sites, determine the functional effects of these specific phosphorylations on phosphatase inhibition, and then prepare phospho-specific antibodies to these sites in order to study the physiological regulation of the state of phosphorylation.