Bargmann C I, Weinberg R A
Whitehead Institute for Biomedical Research, Nine Cambridge Center, MA 02142.
Proc Natl Acad Sci U S A. 1988 Aug;85(15):5394-8. doi: 10.1073/pnas.85.15.5394.
A single mutation altering the transmembrane domain of the receptor-like p185 protein encoded by the rat neu gene converts the normal neu gene into a potent oncogene. The biochemical consequences of this mutation were studied by examining phosphorylation of the normal and transforming p185 molecules in membrane preparations. Here we show that the transforming p185 is phosphorylated to a much higher extent in vitro than its normal counterpart. This preferential phosphorylation has the properties that would be expected of p185 autophosphorylation: it takes place on tyrosine and requires intact p185 kinase activity. The normal p185 protein does not demonstrate increased phosphorylation even when it coexists in a transformed cell with the transforming p185 protein. These data show that transforming p185 is specifically associated with an active tyrosine kinase activity and suggest that this activity is intrinsic to the transforming protein. Thus, the transmembrane domain of p185 appears to directly regulate its kinase activity.
大鼠neu基因编码的类受体p185蛋白的跨膜结构域发生单一突变，可将正常的neu基因转变为一种强效癌基因。通过检测膜制剂中正常和转化型p185分子的磷酸化作用，研究了这种突变的生化后果。我们在此表明，转化型p185在体外的磷酸化程度远高于其正常对应物。这种优先磷酸化具有p185自身磷酸化所预期的特性：它发生在酪氨酸上，并且需要完整的p185激酶活性。即使正常p185蛋白与转化型p185蛋白共存于转化细胞中，它也不会表现出磷酸化增加。这些数据表明，转化型p185与一种活跃的酪氨酸激酶活性特异性相关，并表明这种活性是转化蛋白所固有的。因此，p185的跨膜结构域似乎直接调节其激酶活性。
