THE EPITHELIAL CARCINOMA ANTIGEN EGP-1, RECOGNIZED BY MONOCLONAL-ANTIBODY RS7-3G11, IS PHOSPHORYLATED ON SERINE-303
THE EPITHELIAL CARCINOMA ANTIGEN EGP-1, RECOGNIZED BY MONOCLONAL-ANTIBODY RS7-3G11, IS PHOSPHORYLATED ON SERINE-303
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DOI：
10.1002/ijc.2910620419
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发表时间：
1995-08-09
影响因子：
6.4
通讯作者：
STEIN, R
中科院分区：
文献类型：
--
作者：
BASU, A;GOLDENBERG, DM;STEIN, R
RS7-3GII 是针对人非小细胞肺癌的鼠单克隆抗体 (MAb)，目前正在进行临床评估。由 RS7-3GII 定义的上皮/癌抗原 EGP-I 从宫颈癌细胞系 ME180 中分离并纯化至同质。 EGP-I是一种平均分子量为47.8 kDa的糖蛋白。用 P-32-正磷酸盐对抗原进行代谢标记，随后用 RS7-3GII 进行免疫沉淀，结果表明它是一种磷蛋白。体内磷酸化的EGP-I的磷酸氨基酸分析表明磷酸化是在丝氨酸上。纯化抗原的体外分析表明，蛋白激酶 C（而非蛋白激酶 A）参与体外磷酸化抗原。体外分析表明磷酸化的化学计量为每摩尔EGP-I 0.54摩尔磷酸盐。体外由蛋白激酶C磷酸化的抗原的磷酸氨基酸分析和磷酸肽作图显示，磷酸化发生在丝氨酸残基上，特别是位于EGP-1的细胞质结构域中的丝氨酸303上。用佛波酯处理 ME180 细胞增加了 EGP-I 的磷酸化。 EGP-I的生物学功能仍有待阐明。在本报告中，我们阐明了蛋白激酶 C 参与磷酸化 EGP-I，这可能表明该抗原在跨细胞膜信号转导中的作用。 (C) 1995 Wiley-Liss, Inc.
RS7-3GII is a murine monoclonal antibody (MAb) raised against human non-small-cell lung carcinoma, and is under clinical evaluation. The epithelial/carcinoma antigen EGP-I, defined by RS7-3GII, was isolated and purified to homogeneity from a cervical carcinoma cell line, ME180. EGP-I is a glycoprotein with an average molecular mass of 47.8 kDa. Metabolic labeling of the antigen with P-32-orthophosphate and subsequent immunoprecipitation with RS7-3GII showed that it is a phosphoprotein. Phosphoamino acid analysis of the in vivo phosphorylated EGP-I revealed that the phosphorylation is on serine. In vitro analysis with purified antigen demonstrated that protein kinase C, and not protein kinase A, is involved in phosphorylating the antigen in vitro. In vitro analysis indicated a stoichiometry of phosphorylation of 0.54 mole of phosphate per mole of EGP-I. Phosphoamino acid analysis and phosphopeptide mapping of the antigen phosphorylated in vitro by protein kinase C showed that phosphorylation occurred on a serine residue, specifically on serine 303, located in the cytoplasmic domain of EGP-I. Treatment of ME180 cells with phorbol ester increased the phosphorylation of EGP-I. The biological function of EGP-I remains to be elucidated. In this report we elucidate an involvement of protein kinase C in phosphorylating EGP-I, which may signify a role for this antigen in signal transduction across the cell membrane. (C) 1995 Wiley-Liss, Inc.