Haleem-Smith H, Chang E Y, Szallasi Z, Blumberg P M, Rivera J
Section of Chemical Immunology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892-1820, USA.
Proc Natl Acad Sci U S A. 1995 Sep 26;92(20):9112-6. doi: 10.1073/pnas.92.20.9112.
The delta isoform of protein kinase C is phosphorylated on tyrosine in response to antigen activation of the high-affinity receptor for immunoglobulin E. While protein kinase C-delta associates with and phosphorylates this receptor, immunoprecipitation of the receptor revealed that little, if any, tyrosine-phosphorylated protein kinase C-delta is receptor associated. In vitro kinase assays with immunoprecipitated tyrosine-phosphorylated protein kinase C-delta showed that the modified enzyme had diminished activity toward the receptor gamma-chain peptide as a substrate but not toward histones or myelin basic protein peptide. We propose a model in which the tyrosine phosphorylation of protein kinase C-delta regulates the kinase specificity toward a given substrate. This may represent a general mechanism by which in vivo protein kinase activities are regulated in response to external stimuli.
免疫球蛋白E高亲和力受体抗原激活后，蛋白激酶C的δ亚型会在酪氨酸位点发生磷酸化。虽然蛋白激酶C-δ与该受体结合并使其磷酸化，但对该受体进行免疫沉淀后发现，与受体相关的酪氨酸磷酸化蛋白激酶C-δ极少（如果有的话）。用免疫沉淀的酪氨酸磷酸化蛋白激酶C-δ进行的体外激酶分析表明，修饰后的酶对受体γ链肽作为底物的活性降低，但对组蛋白或髓鞘碱性蛋白肽的活性未降低。我们提出了一个模型，其中蛋白激酶C-δ的酪氨酸磷酸化调节激酶对给定底物的特异性。这可能代表了一种普遍机制，通过该机制体内蛋白激酶活性可响应外部刺激进行调节。
