THE GROWTH FACTOR-INDUCIBLE IMMEDIATE-EARLY GENE 3CH134 ENCODES A PROTEIN-TYROSINE-PHOSPHATASE
THE GROWTH FACTOR-INDUCIBLE IMMEDIATE-EARLY GENE 3CH134 ENCODES A PROTEIN-TYROSINE-PHOSPHATASE
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DOI：
10.1073/pnas.90.11.5292
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发表时间：
1993-06-01
影响因子：
11.1
通讯作者：
TONKS, NK
中科院分区：
文献类型：
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作者：
CHARLES, CH;SUN, H;TONKS, NK
用血清生长因子刺激成纤维细胞可导致一组即时早期基因的快速激活，其中包括3CH134。我们纯化了3ch134编码多肽的细菌表达形式，并证明它具有内在的蛋白酪氨酸-磷酸酶（PTPase；蛋白酪氨酸-磷酸磷酸化水解酶，EC 3.1.3.48）活性。这种活性在pH 7.5时最理想，对钒酸盐和半胱氨酸修饰剂敏感，对一组丝氨酸/苏氨酸磷酸酶抑制剂不敏感。纯化后的3CH134蛋白在酪氨酸磷酸化多肽底物中表现出高度的选择性。在我们的实验条件下，去磷酸化的速率顺序为EDNDYINASL肽<髓鞘碱性蛋白<还原，羧胺甲基化和马来酰化溶菌酶(RCML) < p42mapk。这些底物的速率范围是200倍，p42mapk的去磷酸化速度比RCML快15倍。虽然3CH134与酪氨酸/丝氨酸双特异性磷酸酶VH1最密切相关，但我们未能检测到任何3CH134对酪蛋白或被camp依赖性蛋白激酶磷酸化的丝氨酸/苏氨酸残基的RCML的活性。由于3CH134的表达受到转录和转录后的控制，它可能代表了一类活性在蛋白质合成和降解水平上受到调节的PTPases。
Stimulation of fibroblasts with serum growth factors results in the rapid activation of a set of immediate-early genes, among them 3CH134. We have purified a bacterially expressed form of the 3CH134-encoded polypeptide and demonstrated that it has intrinsic protein-tyrosine-phosphatase (PTPase; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) activity in vitro. This activity is optimal at pH 7.5, is sensitive to vanadate and cysteinyl modifying agents, and is insensitive to a panel of serine/threonine phosphatase inhibitors. Purified 3CH134 protein displays a high degree of selectivity among the tyrosine-phosphorylated polypeptide substrates tested. Under our assay conditions, the rates of dephosphorylation are in the order EDNDYINASL peptide < myelin basic protein < reduced, carboxyamidomethylated, and maleylated lysozyme (RCML) < p42mapk. There is a 200-fold range in rates for these substrates, with p42mapk dephosphorylated 15-fold more rapidly than RCML. Although 3CH134 is most closely related to the tyrosine/serine dual-specificity phosphatase VH1, we failed to detect any 3CH134-directed activity on casein or RCML phosphorylated on serine/threonine residues by cAMP-dependent protein kinase. Since 3CH134 expression is controlled transcriptionally and posttranscriptionally, it may represent a class of PTPases whose activity is regulated at the level of protein synthesis and degradation.