Pike L J, Kuenzel E A, Casnellie J E, Krebs E G
J Biol Chem. 1984 Aug 10;259(15):9913-21.
The characteristics of the insulin- and epidermal growth factor (EGF)-stimulated tyrosine-specific protein kinases in a wheat germ lectin-Sepharose-purified preparation of solubilized placenta membranes were compared. The specific activity of the insulin-stimulated kinase in this preparation was 72 nmol/min/mg whereas the specific activity of the EGF-stimulated kinase was 312 nmol/min/mg using a synthetic peptide as the phosphorylatable substrate. The two enzymes showed similar divalent metal ion requirements and nucleotide specificities. In addition, both kinases were inhibited by treatment with N-ethylmaleimide. However, the EGF-stimulated enzyme was more sensitive to modification by this reagent than was the insulin-stimulated kinase. When examined for their ability to utilize a number of different proteins as substrates, the insulin- and EGF-stimulated kinases exhibited similar but not identical substrate specificities. These similarities at the molecular level may be the basis of the similarity between the actions of insulin and EGF at the cellular level.
比较了在麦胚凝集素-琼脂糖纯化的可溶性胎盘膜制剂中，胰岛素和表皮生长因子（EGF）刺激的酪氨酸特异性蛋白激酶的特性。使用合成肽作为可磷酸化底物时，该制剂中胰岛素刺激激酶的比活性为72 nmol/分钟/毫克，而EGF刺激激酶的比活性为312 nmol/分钟/毫克。这两种酶显示出相似的二价金属离子需求和核苷酸特异性。此外，两种激酶都被N-乙基马来酰亚胺处理所抑制。然而，EGF刺激的酶比胰岛素刺激的激酶对该试剂的修饰更敏感。当检测它们利用多种不同蛋白质作为底物的能力时，胰岛素和EGF刺激的激酶表现出相似但不完全相同的底物特异性。分子水平上的这些相似性可能是胰岛素和EGF在细胞水平上作用相似性的基础。
