Haycock J W
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans 70119.
Brain Res Bull. 1987 Dec;19(6):619-22. doi: 10.1016/0361-9230(87)90046-3.
Incubation of rat corpus striatal synaptosomes with 32PO4 led to a time-dependent incorporation of 32P into tyrosine hydroxylase. Depolarization of the synaptosomes with elevated [K+]o increased 32P incorporation into tyrosine hydroxylase. The depolarization-dependent increase in 32P incorporation into tyrosine hydroxylase occurred rapidly (less than 15 sec), persisted in the presence of elevated [K+]o (up to 120 sec), required the presence of [Ca++]o, and was associated with serine (but not threonine or tyrosine) residues. After limit tryptic digestion of the 32P-tyrosine hydroxylase, several phosphopeptides were separated by HPLC, and elevated [K+]o increased 32P incorporation into two of these phosphopeptides. Thus, depolarization of dopaminergic terminals from the rat corpus striatum increased the phosphorylation of tyrosine hydroxylase, and the increase in phosphorylation appeared to occur at multiple sites. Multiple-site phosphorylation of tyrosine hydroxylase has been previously shown in peripheral catecholaminergic tissues. However, substantial differences in the elution profiles of tyrosine hydroxylase phosphopeptides from striatal synaptosomes and from bovine adrenal chromaffin cells were observed. Thus, qualitative differences in the regulation of tyrosine hydroxylase may exist among the many catecholaminergic systems.
用32PO4孵育大鼠纹状体突触体导致32P随时间依赖性地掺入酪氨酸羟化酶。用升高的[K+]o使突触体去极化可增加32P掺入酪氨酸羟化酶。32P掺入酪氨酸羟化酶的去极化依赖性增加迅速发生（少于15秒），在升高的[K+]o存在下持续存在（长达120秒），需要[Ca++]o存在，并且与丝氨酸（而非苏氨酸或酪氨酸）残基相关。对32P-酪氨酸羟化酶进行有限胰蛋白酶消化后，通过HPLC分离出几种磷酸肽，升高的[K+]o增加了32P掺入其中两种磷酸肽。因此，大鼠纹状体多巴胺能终末的去极化增加了酪氨酸羟化酶的磷酸化，且磷酸化增加似乎发生在多个位点。酪氨酸羟化酶的多位点磷酸化先前已在外周儿茶酚胺能组织中显示。然而，观察到纹状体突触体和牛肾上腺嗜铬细胞中酪氨酸羟化酶磷酸肽洗脱图谱存在实质性差异。因此，许多儿茶酚胺能系统之间可能存在酪氨酸羟化酶调节的质的差异。
