Gaudino G, Cilli M, Gandino L, Rossino P, Mondino A, Comoglio P M
Department of Biomedical Sciences and Oncology, University of Torino Medical School, Italy.
Ann N Y Acad Sci. 1988;547:293-302. doi: 10.1111/j.1749-6632.1988.tb23897.x.
In Swiss 3T3 fibroblasts, antibodies which recognize a phosphotyrosine residue (P-Tyr antibodies) identify a 115-kDa cell surface protein (p115) that becomes phosphorylated on tyrosine as a response to bombesin stimulation of quiescent cells. The extent of phosphorylation is dose-dependent and correlates with the mitogenic effect induced by bombesin, measured by [3H]thymidine incorporation. Tyrosine phosphorylation of p115 is detectable minutes after addition of bombesin and precedes the activation of c-fos and c-myc gene transcription. Immunocomplexes of phosphorylated p115 with P-Tyr antibodies bind 125I-labeled [Tyr4]bombesin in a specific and saturable manner and display an associated tyrosine protein kinase activity enhanced by bombesin. P-Tyr antibodies also recognize a protein of 115 kDa, phosphorylated at tyrosine, in four human SCLC lines producing bombesin but not in a non-producer "variant" line. Phosphorylation of SCLC p115 does not require the addition of exogenous bombesin. As in the case of the p115 immunoprecipitated from mouse fibroblasts, the SCLC p115 is phosphorylated in an immunocomplex kinase assay. These observations are in agreement with the hypothesis of autocrine activation of bombesin receptors in human small cell lung carcinoma cells.
在瑞士3T3成纤维细胞中，识别磷酸酪氨酸残基的抗体（抗磷酸酪氨酸抗体）可鉴定出一种115 kDa的细胞表面蛋白（p115），该蛋白在静止细胞受到蛙皮素刺激时会在酪氨酸上发生磷酸化。磷酸化程度呈剂量依赖性，并且与蛙皮素诱导的促有丝分裂效应相关，该效应通过[3H]胸苷掺入来测定。加入蛙皮素后几分钟即可检测到p115的酪氨酸磷酸化，且早于c-fos和c-myc基因转录的激活。磷酸化的p115与抗磷酸酪氨酸抗体形成的免疫复合物以特异性和饱和性方式结合125I标记的[酪氨酸4]蛙皮素，并显示出一种由蛙皮素增强的相关酪氨酸蛋白激酶活性。抗磷酸酪氨酸抗体在四种产生蛙皮素的人小细胞肺癌细胞系中也识别一种115 kDa、在酪氨酸处磷酸化的蛋白，但在一个不产生蛙皮素的“变异”细胞系中则不识别。人小细胞肺癌细胞系中p115的磷酸化不需要添加外源性蛙皮素。与从小鼠成纤维细胞免疫沉淀的p115情况一样，人小细胞肺癌细胞系中的p115在免疫复合物激酶测定中发生磷酸化。这些观察结果与人类小细胞肺癌细胞中蛙皮素受体自分泌激活的假说一致。
