TYROSINE PHOSPHATASES AND INSULIN RESISTANCE IN THE AGED

一种合成的三磺基酪氨酰十二肽[TRDIY[S]ETDY[S]Y[S]RK- 酰胺]，其一级序列与SEQ ID NO：1142-1153序列相同。 胰岛素前受体，抑制胰岛素受体去磷酸化， 溶解的膜和毛地黄皂苷透化的细胞， 中国仓鼠卵巢[CHO]细胞表达高水平的人 胰岛素受体[CHO/HIRc]。 它还能抑制 通过重组PTP-1B合成的酪氨酸磷酸化底物， 蛋白酪氨酸磷酸酶（PTK），表明它通过 与PTT的相互作用。 肽的N-硬脂基衍生物引起 胰岛素刺激受体自身磷酸化增加约4.5倍， 完整CHO/HIRc细胞。 该肽对酪氨酸- 类磷酸酶，因为它没有影响的活动， 丝氨酸/苏氨酸磷酸酶PP-1和PP-2A或碱性磷酸酶。 肽的酪氨酸硫酸酯键是稳定的， 与PTP-1B孵育（1小时，30 ℃）。 这些数据表明 磺基酪氨酰肽起不可水解的磷酸酪氨酰的作用 能够与PTK催化剂直接相互作用的肽类似物 域

A synthetic tris-sulfotyrosyl dodecapeptide [TRDIY[S]ETDY[S]Y[S]RK- amide], whose primary sequence is identical to the 1142-1153 sequence of the insulin proreceptor, inhibited insulin receptor dephosphorylation in solubilized membranes, and digitonin-permeabilized cells derived from Chinese hamster ovary [CHO] cells expressing high levels of human insulin receptors [CHO/HIRc]. It also inhibited the dephosphorylation of a synthetic tyrosine phosphorylated substrate by recombinant PTP-1B, a protein tyrosine phosphatase (PTPase), indicating that it acted via interaction with PTPase(s). A N-stearyl derivative of the peptide caused an ~4.5-fold increase in insulin-stimulated receptor autophosphorylation in intact CHO/HIRc cells. The peptide displayed specificity toward tyrosine- class phosphatases only, as it had no effect on the activities of the serine/threonine phosphatases PP-1 and PP-2A, or alkaline phosphatase. The tyrosine sulfate ester bonds of the peptide were stable when incubated with PTP-1B (1h, 300 C). These data suggest that the sulfotyrosyl peptide functions as a nonhydrolyzable phosphotyrosyl peptide analogue capable of direct interaction with PTPase catalytic domain.