Molecular cloning and expression of a unique receptor-like protein-tyrosine-phosphatase in the leucocyte-common-antigen-related phosphate family.
Molecular cloning and expression of a unique receptor-like protein-tyrosine-phosphatase in the leucocyte-common-antigen-related phosphate family.
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白细胞共同抗原相关磷酸家族中独特受体样蛋白酪氨酸磷酸酶的分子克隆和表达。
DOI：
10.1042/bj3020039
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Goldstein,BJ
中科院分区：
文献类型：
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作者：
Zhang,WR;Hashimoto,N;Ahmad,F;Ding,W;Goldstein,BJ
蛋白酪氨酸磷酸酶（PTPases）与某些酪氨酸激酶生长因子受体的调节有关，因为它们使激活的受体（自磷酸化）去磷酸化。为了鉴定可能作用于肝脏受体靶点的PTPase，我们使用了人白细胞共同抗原相关PTPase (LAR) cDNA [Streuli, Krueger, Hall, Schlossman and Saito (1988) J. Exp. Med. 168,1523 -1530]，并从大鼠肝脏cDNA文库中分离出两个密切相关的跨膜PTPase同源物。两种PTPases都有较大的胞外结构域，包含3个免疫球蛋白样重复序列和8个iii型纤维连接蛋白重复序列。这两种酶在一个疏水跨膜结构域之后具有串联同源PTPase结构域。其中一个序列编码LAR的大鼠同源物。第二个PTPase，被命名为LAR- ptp2，在各自的细胞质PTPase结构域与大鼠LAR有79%和90%的相似性，在细胞外结构域只有57%的序列相似性。细菌表达制备的LAR和LAR- ptp2的催化结构域对多种磷酸化酪氨酸底物具有去磷酸化活性，但不水解标记酪蛋白的磷酸丝氨酸或磷酸苏氨酸残基。髓鞘碱性蛋白和衍生溶菌酶的快速周转数分别为4-7 s-1和78-150 s-1。LAR和LAR- ptp2对肝膜完整胰岛素和表皮生长因子受体的同时去磷酸化表现出相似的PTPase活性。这些数据表明，在肝脏和其他组织中，存在一个与lar相关的PTPases家族，可能调节受体酪氨酸激酶的磷酸化状态。
Protein-tyrosine-phosphatases (PTPases) have been implicated in the regulation of certain tyrosine kinase growth factor receptors in that they dephosphorylate the activated (autophosphorylated) form of the receptors. In order to identify PTPases that potentially act on receptor targets in liver, we used the human leucocyte common antigen-related PTPase (LAR) cDNA [Streuli, Krueger, Hall, Schlossman and Saito (1988) J. Exp. Med. 168, 1523-1530] and isolated two closely related transmembrane PTPase homologues from a rat hepatic cDNA library. Both PTPases had large extracellular domains that contained three immunoglobulin-like repeats and eight type-III fibronectin repeats. Both enzymes had tandem homologous PTPase domains following a single hydrophobic transmembrane domain. One sequence encoded the rat homologue of LAR. The second PTPase, designated LAR-PTP2, had 79 and 90% identity with rat LAR in the respective cytoplasmic PTPase domains, with only 57% sequence similarity in the extracellular domain. The catalytic domains of LAR and LAR-PTP2 prepared by bacterial expression were active in dephosphorylating a variety of phosphotyrosyl substrates but did not hydrolyse phosphoserine or phosphothreonine residues of labelled casein. Both enzymes exhibited rapid turnover numbers of 4-7 s-1 for myelin basic protein and 78-150 s-1 for derivatized lysozyme. LAR and LAR-PTP2 displayed similar PTPase activity towards the simultaneous dephosphorylation of receptors of intact insulin and epidermal growth factor from liver membranes. These data indicate that there is a family of LAR-related PTPases that may regulate the phosphorylation state of receptor tyrosine kinases in liver and other tissues.