Riedel H, Wang J, Hansen H, Yousaf N
Department of Biological Sciences, Karmanos Cancer Institute, Wayne State University, Detroit, MI 48202, USA.
J Biochem. 1997 Dec;122(6):1105-13. doi: 10.1093/oxfordjournals.jbchem.a021868.
Insulin stimulation results in a considerable spectrum of cellular responses, only part of which have been firmly correlated with the activation of established insulin receptor (IR) targets such as IRS-1, IRS-2, and Shc. Many responses may be transduced by alternative direct IR targets, some of which may still be unknown, may act in parallel to but independently of IRS-1, IRS-2, and Shc, and may be members of the growing family of SH2 domain-containing signaling adaptors. An SH2 domain-coding region of a protein termed PSM was cloned based on its interaction with an activated IR cytoplasmic fragment in a yeast two-hybrid screen. When used as a hybridization probe this region led to the isolation of a protein-coding cDNA which is expressed with a wide tissue distribution and exists in several variant forms. A pleckstrin homology domain and three Pro-rich regions including a putative SH3 domain binding site were identified in addition to the SH2 domain in the deduced 756 amino acid sequence. They imply a role of PSM in tyrosine kinase and phosphatase-mediated signaling pathways. A similar sequence termed SH2-B had been reported in an earlier study, which may represent the rat homolog of PSM. A role of PSM specifically in insulin action is suggested by the interaction of its SH2 domain with an activated but not with an inactive catalytic fragment of the IR in the yeast two-hybrid system in vivo, by the insulin-dependent association of a glutathione S-transferase (GST) PSM SH2 domain fusion protein with purified IR in vitro, and by the insulin-dependent association of GST PSM SH2 with the IR in cell extracts. In contrast, PSM was not found to associate with the established IR substrate IRS-1 under any conditions and appears to act independently of IRS-1. All of our findings are compatible with a putative role of PSM in insulin action.
胰岛素刺激会引发一系列相当广泛的细胞反应，其中只有一部分与已确定的胰岛素受体（IR）靶点（如IRS-1、IRS-2和Shc）的激活有明确关联。许多反应可能由其他直接的IR靶点介导，其中一些可能仍不为人知，它们可能与IRS-1、IRS-2和Shc并行但独立发挥作用，并且可能是不断增加的含SH2结构域的信号转导衔接蛋白家族的成员。一种名为PSM的蛋白质的SH2结构域编码区，是基于其在酵母双杂交筛选中与活化的IR细胞质片段的相互作用而克隆得到的。当用作杂交探针时，该区域导致分离出一个蛋白质编码cDNA，其在广泛的组织中表达，并以几种变体形式存在。在推导的756个氨基酸序列中，除了SH2结构域外，还鉴定出一个普列克底物蛋白同源结构域和三个富含脯氨酸的区域，包括一个假定的SH3结构域结合位点。它们暗示PSM在酪氨酸激酶和磷酸酶介导的信号通路中发挥作用。早期研究中报道了一个类似的序列，称为SH2-B，它可能代表PSM的大鼠同源物。PSM在胰岛素作用中的特定作用，是由其SH2结构域在体内酵母双杂交系统中与活化的而非无活性的IR催化片段的相互作用、体外谷胱甘肽S-转移酶（GST）-PSM SH2结构域融合蛋白与纯化的IR的胰岛素依赖性结合，以及GST-PSM与细胞提取物中IR的胰岛素依赖性结合所表明的。相比之下，在任何条件下都未发现PSM与已确定的IR底物IRS-1相关联，并且似乎独立于IRS-1发挥作用。我们所有的发现都与PSM在胰岛素作用中的假定作用相符。
