PHOSPHORYLATION ACTIVATES THE INSULIN-RECEPTOR TYROSINE PROTEIN-KINASE
PHOSPHORYLATION ACTIVATES THE INSULIN-RECEPTOR TYROSINE PROTEIN-KINASE
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DOI：
10.1073/pnas.80.11.3237
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
COBB, MH
中科院分区：
文献类型：
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作者：
ROSEN, OM;HERRERA, R;COBB, MH
从培养的3T3-L1脂肪细胞和人胎盘制备的胰岛素受体先前催化了胰岛素受体90,000道尔顿组分在酪氨酸残基上的磷酸化。这种依赖于胰岛素的磷酸化现在被证明与激活的、非依赖于胰岛素的受体蛋白激酶的产生是一致的。激活依赖于三磷酸腺苷、二价阳离子(镁和锰)和胰岛素(胰岛素在6-8 nM时出现半最大激活)。激活所需的时间与小麦胚凝集素-琼脂糖柱洗脱液和亲和纯化胎盘受体制备中存在的胰岛素依赖的自我磷酸化受体所需的时间一致。在0.1 mg/ml的大豆胰蛋白酶抑制剂存在下，激活继续进行，并且激活的、不依赖于胰岛素的蛋白激酶沉积在5-20%的蔗糖梯度中，与未修饰的受体处于相同的位置。在稳态条件下，磷酸化的受体与胰岛素的结合方式与未经修饰的受体相同。有人认为，该受体的自身磷酸化形式是胰岛素激活的蛋白激酶，它催化外源蛋白和肽底物的磷酸化。这一假设的一个推论是，酶去磷酸化可能是可逆地终止胰岛素受体蛋白激酶活性的关键。
Preparations of insulin receptor from cultured [mouse] 3T3-L1 adipocytes and human placenta previously catalyzed the phosphorylation of the 90,000-dalton component of the insulin receptor on tyrosine residues. This insulin-dependent phosphorylation has now been shown to coincide with the generation of an activated, insulin-independent, receptor protein kinase. Activation is dependent upon ATP, divalent cations (Mg2+ and Mn2+), and insulin (half-maximal activation occurs at 6-8 nM insulin). The time required for activation is consistent with that needed for insulin-dependent self-phosphorylation of the receptor present in eluates from wheat germ lectin-agarose columns and in preparations of affinity-purified placental receptor. Activation proceeds unabated in the presence of soybean trypsin inhibitor at 0.1 mg/ml and the activated, insulin-independent, protein kinase sediments in 5-20% sucrose gradients at the same position as the unmodified receptor. Under steady-state conditions, the phosphorylated receptor binds insulin in the same fashion as the unmodified receptor. It is proposed that the self-phosphorylated form of the receptor is the insulin-activated protein kinase that catalyzes the phosphorylation of exogenous protein and peptide substrates. A corollary of this hypothesis is that enzymatic dephosphorylation may be essential for reversibly terminating the activity of the insulin-receptor protein kinase.