Tuveson D A, Carter R H, Soltoff S P, Fearon D T
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Science. 1993 May 14;260(5110):986-9. doi: 10.1126/science.7684160.
Antigen receptors on B and T lymphocytes transduce signals by activating nonreceptor protein tyrosine kinases (PTKs). A family of receptor PTKs contains kinase insert regions with the sequence tyrosine-X-X-methionine (where X is any amino acid) that when phosphorylated mediate the binding and activation of phosphatidylinositol 3-kinase (PI 3-kinase). The CD19 membrane protein of B cells enhances activation through membrane immunoglobulin M (mIgM) and was found to contain a functional analog of the kinase insert region. Ligation of mIgM induced phosphorylation of CD19 and association with PI 3-kinase. Thus, CD19 serves as a surrogate kinase insert region for mIgM by providing the means for PI 3-kinase activation by nonreceptor PTKs.
B淋巴细胞和T淋巴细胞上的抗原受体通过激活非受体蛋白酪氨酸激酶（PTK）来转导信号。一类受体PTK含有激酶插入区域，其序列为酪氨酸-X-X-甲硫氨酸（其中X为任意氨基酸），磷酸化后可介导磷脂酰肌醇3激酶（PI 3激酶）的结合与激活。B细胞的CD19膜蛋白通过膜免疫球蛋白M（mIgM）增强激活作用，并且发现其含有激酶插入区域的功能类似物。mIgM的连接诱导CD19磷酸化并与PI 3激酶结合。因此，CD19通过提供非受体PTK激活PI 3激酶的方式，作为mIgM的替代激酶插入区域。
