期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：9
页码：2604-2608
DOI：10.1073/pnas.69.9.2604
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Essentially no specific binding sites for insulin are detected in small lymphocytes freshly isolated from human blood. Insulin-binding sites appear on the lymphocyte surface during transformation in vitro with concanavalin A, and the number of these receptors increases sharply to reach a maximum between 24 and 46 hr after exposure to the mitogen. The appearance of de novo binding sites for insulin coincides with the increase in [3H]thymidine uptake into nuclear DNA and clearly precedes the appearance of enlarged, morphologically transformed cells. No changes in insulin-binding are detected in unstimulated control cultures. A maximum of about 350 molecules of insulin can bind per transformed lymphocyte, while less than six insulin molecules bind to an untransformed cell. Circulating human leukemic lymphoblasts bind about as much insulin as the lymphocytes transformed in vitro. Giant, polynucleated, transformed lymphocytes cultured in the presence of cytochalasin B bind about 10 times more insulin than transformed lymphocytes, which is in harmony with a 10-fold increase in cell-surface area in these cells. Specific binding of insulin is a saturable process in transformed lymphocytes but not in the untransformed cells. In transformed cells, [125I]-insulin is displaced by as little as 2 ng/ml of native insulin, while in untransformed cells no significant displacement is observed with native insulin. Digestion of transformed cells with phospholipase C (EC 3.1.4.3 .) enhances the specific binding of [125I]insulin 3-fold, but no effect occurs with untransformed cells. These observations indicate a possible functional role of insulin and of adenylate cyclase in cell growth and division.
关键词：concanavalin A ; cell growth and division ; insulin receptors
