Cheng Haipeng, Gao Qi, Jiang Min, Ma Yushu, Ni Xiaohua, Guo Lingchen, Jin Wei, Cao Gentao, Ji Chaoneng, Ying Kang, Xu Weiwen, Gu Shaohua, Ma Yuhong, Xie Yi, Mao Yumin
State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan University, 200433, Shanghai, PR China
Int J Biochem Cell Biol. 2003 Feb;35(2):226-34. doi: 10.1016/s1357-2725(02)00127-9.
Reversible phosphorylation is recognized to be a major mechanism for the control of intracellular events in eukaryotic cells. From a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel dual specificity protein phosphatase, which showed 88% identity with previously reported mouse LMW-DSP3 at the amino acid level. The deduced protein had a single dual-specificity phosphatase catalytic domain, and lacked a cdc25 homology domain. LMW-DSP3 was expressed in the heart, lung, liver, and pancreas, and the expression level in the pancreas was highest. The LMW-DSP3 gene was located in human chromosome 2q32, and consisted of five exons spanning 21kb of human genomic DNA. LMW-DSP3 fused to GST showed phosphatase activity towards p-nitrophenyl phosphate which was optimal at pH 7.0 and 40 degrees C, and the activity was enhanced by Ca(2+) and Mn(2+). The phosphatase activity of LMW-DSP3 was inhibited by orthovanate. LMW-DSP3 showed phosphatase activity toward oligopeptides containing pSer/Thr and pTyr, indicating that LMW-DSP3 is a protein phosphatase with dual substrate specificity.
可逆磷酸化被认为是真核细胞中控制细胞内事件的主要机制。我们从人胎脑cDNA文库中分离出一个编码新型双特异性蛋白磷酸酶的cDNA克隆，该克隆在氨基酸水平上与先前报道的小鼠LMW-DSP3具有88%的同一性。推导的蛋白质具有单个双特异性磷酸酶催化结构域，并且缺乏cdc25同源结构域。LMW-DSP3在心脏、肺、肝脏和胰腺中表达，在胰腺中的表达水平最高。LMW-DSP3基因位于人类染色体2q32，由跨越21kb人类基因组DNA的五个外显子组成。与GST融合的LMW-DSP3对磷酸对硝基苯酯显示出磷酸酶活性，在pH 7.0和40℃时活性最佳，并且Ca(2+)和Mn(2+)可增强该活性。LMW-DSP3的磷酸酶活性被原钒酸盐抑制。LMW-DSP3对含有pSer/Thr和pTyr的寡肽显示出磷酸酶活性，表明LMW-DSP3是一种具有双底物特异性的蛋白磷酸酶。
