Johansen P A, Jennings I, Cotton R G, Kuhn D M
Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA.
J Neurochem. 1995 Aug;65(2):882-8. doi: 10.1046/j.1471-4159.1995.65020882.x.
The effect of protein kinase A on the catalytic activity and phosphorylation of brain tryptophan hydroxylase was examined. Stimulation of endogenous protein kinase A by cyclic AMP or its analogues, dibutyryl-cyclic AMP and 8-thiomethyl-cyclic AMP, failed to activate tryptophan hydroxylase. The activation of tryptophan hydroxylase by calcium/calmodulin-phosphorylating conditions was not modified by cyclic AMP. Endogenous protein kinase A phosphorylated a large number of proteins and tryptophan hydroxylase could be identified as one substrate by sucrose gradient centrifugation, immunoprecipitation, and immunoblotting. These results indicate that tryptophan hydroxylase is phosphorylated by protein kinase A in brain and question whether this protein kinase exerts direct regulatory influence over tryptophan hydroxylase activity via phosphorylation.
研究了蛋白激酶A对脑色氨酸羟化酶催化活性和磷酸化作用的影响。用环磷酸腺苷（cAMP）或其类似物二丁酰环磷酸腺苷（dibutyryl-cyclic AMP）和8-硫代甲基环磷酸腺苷（8-thiomethyl-cyclic AMP）刺激内源性蛋白激酶A，未能激活色氨酸羟化酶。环磷酸腺苷未改变钙/钙调蛋白磷酸化条件下色氨酸羟化酶的激活作用。内源性蛋白激酶A使大量蛋白质发生磷酸化，通过蔗糖梯度离心、免疫沉淀和免疫印迹可将色氨酸羟化酶鉴定为一种底物。这些结果表明，脑内色氨酸羟化酶可被蛋白激酶A磷酸化，同时也对这种蛋白激酶是否通过磷酸化对色氨酸羟化酶活性发挥直接调节作用提出了疑问。
