Lim N, Wijaya E, Ng F
Department of Biochemistry, Monash University, Clayton, Victoria, Australia.
Life Sci. 1994;54(20):1471-81. doi: 10.1016/0024-3205(94)90014-0.
The in vitro effect of a hypoglycaemic fragment of human growth hormone containing the sequence H2N-Leu-Ser-Arg-Leu-Phe-Asu11-Asn-Ala-COOH (Asu11-hGH 6-13) on tyrosine kinase of rat hepatic insulin receptors was examined. Insulin receptor kinase activity was evaluated using the synthetic polypeptide poly(Glu-Tyr)(4:1) as substrate. The hypoglycaemic Asu11-hGH 6-13 appeared to enhance the phosphorylation of the exogenous substrate by the stimulation of insulin receptor kinase activity. The levels of poly(Glu-Tyr)(4:1) phosphorylation were significantly higher in the insulin receptor preparations incubated in the presence of the Asu11-hGH 6-13 peptide. A dose dependent stimulation of receptor kinase activity was observed and this stimulatory effect was found to be further enhanced by the addition of increasing concentrations of insulin. In hepatic extracts depleted of insulin receptor, no stimulation of kinase activity by the Asu11-hGH 6-13 was observed. From these data, it is concluded that the increase of poly (Glu-Tyr) (4:1) phosphorylation is the result of the interaction between the Asu11-hGH 6-13 and the hepatic insulin receptor.
研究了含序列H2N-亮氨酸-丝氨酸-精氨酸-亮氨酸-苯丙氨酸-天冬酰胺11-天冬酰胺-丙氨酸-COOH（天冬酰胺11-人生长激素6-13）的人生长激素降血糖片段对大鼠肝脏胰岛素受体酪氨酸激酶的体外作用。以合成多肽聚（谷氨酸-酪氨酸）（4:1）为底物评估胰岛素受体激酶活性。降血糖的天冬酰胺11-人生长激素6-13似乎通过刺激胰岛素受体激酶活性增强了外源底物的磷酸化。在存在天冬酰胺11-人生长激素6-13肽的情况下孵育的胰岛素受体制剂中，聚（谷氨酸-酪氨酸）（4:1）的磷酸化水平显著更高。观察到受体激酶活性呈剂量依赖性刺激，并且发现通过添加浓度不断增加的胰岛素，这种刺激作用会进一步增强。在耗尽胰岛素受体的肝脏提取物中，未观察到天冬酰胺11-人生长激素6-13对激酶活性的刺激。根据这些数据得出结论，聚（谷氨酸-酪氨酸）（4:1）磷酸化的增加是天冬酰胺11-人生长激素6-13与肝脏胰岛素受体相互作用的结果。
