Cloning of a human phosphoinositide 3-kinase with a C2 domain that displays reduced sensitivity to the inhibitor wortmannin
Cloning of a human phosphoinositide 3-kinase with a C2 domain that displays reduced sensitivity to the inhibitor wortmannin
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DOI：
10.1042/bj3260139
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发表时间：
1997-08-15
影响因子：
4.1
通讯作者：
Waterfield, MD
中科院分区：
文献类型：
--
作者：
Domin, J;Pages, F;Waterfield, MD
磷脂酰肌醇 3-磷酸的生成已在多种细胞反应中观察到。介导合成的酶是磷酸肌醇 3-激酶 (PI3-K)，它们形成具有不同底物特异性的结构多样的酶家族。在本文中，我们描述了新型人类 PI3-K 的克隆，即 PI3-K-C2 α，它包含 C 末端 C2 结构域。该酶可归为 II 类 PI3-K，其通过果蝇 68D 酶的表征定义，包括最近描述的鼠酶 m-cpk 和 p170。尽管鼠类和人类酶的氨基酸序列总体相似，这表明它们是由密切相关的基因编码的，但这些分子在其 N 末端显示出明显的序列异质性。重组 PI3-K-C2 α 的生化分析表明脂质底物特异性有限。正如该类其他成员所报道的，当脂质单独存在时，该酶仅磷酸化 PtdIns 和 PtdIns4P，然而，当脂质与作为载体的磷脂酰丝氨酸一起存在时，也观察到 PtdIns(4,5)P-2 的磷酸化。其他家族成员的 PI3-K 活性，PI3-K-C2 α 对这些抑制剂的相对不敏感性表明，在 PI3-Ks 研究中应重新评估它们的使用。
The generation of phosphatidylinositide 3-phosphates has been observed in a variety of cellular responses, The enzymes that mediate synthesis are the phosphoinositide 3-kinases (PI3-Ks) that form a family of structurally diverse enzymes with distinct substrate specificities. In this paper, we describe the cloning of a novel human PI3-K, namely PI3-K-C2 alpha, which contains a C-terminal C2 domain, This enzyme can be assigned to the class II PI3-Ks, which was defined by characterization of the Drosophila 68D enzyme and includes the recently described murine enzymes m-cpk and p170. Despite the overall similarity in the amino acid sequence of the murine and human enzymes, which suggests that they are encoded by closely related genes, these molecules show marked sequence heterogeneity at their N-termini. Biochemical analysis of recombinant PI3-K-C2 alpha demonstrates a restricted lipid substrate specificity. As reported for other members of this class, the enzyme only phosphorylates PtdIns and PtdIns4P when the lipids are presented alone, However, when lipids were presented together with phosphatidylserine acting as a carrier, phosphorylation of PtdIns(4,5)P-2 was also observed, The catalytic activity of PI3-K-C2 alpha is refractory to concentrations of wortmannin and LY294002 which inhibit the PI3-K activity of other family members, The comparative insensitivity of PI3-K-C2 alpha to these inhibitors suggests that their use should be reevaluated in the study of PI3-Ks.