Bastien L, Ramachandran C, Liu S, Adam M
Department of Molecular Biology, Merck Frosst Centre for Therapeutic Research Research, Pointe Claire-Dorval, Quebec, Canada.
Biochem Biophys Res Commun. 1993 Oct 15;196(1):124-33. doi: 10.1006/bbrc.1993.2224.
A human cDNA clone encoding a nonreceptor protein-tyrosine-phosphatase (PTP) has been isolated and sequenced. The 2.1 kilobase pair cDNA encodes for a 593 amino acid protein that contains a single tyrosine phosphatase catalytic domain at the C-terminus. At the N-terminus the protein has two adjacent copies of Src homology region (SH2 domain) which show 61% and 73% identity at the amino acid level to the SH2 domains of the human PTP1C and Drosophila corkscrew protein, respectively. The overall homology between SH-PTP2 and PTP1C or to corkscrew protein is 58%. When this protein (or its catalytic domain) was expressed in E. coli as a glutathione-S-transferase fusion protein tyrosine-phosphatase activity was detected in bacterial cell extracts. Site-directed mutation made at the conserved cysteine (459) residue to serine within the highly conserved VHCXAGXXR sequence in the PTP catalytic domain resulted in complete loss of enzymatic activity demonstrating the importance of this cysteine residue in catalysis. Northern blot analysis showed that SH-PTP2 is expressed as a 6.5 kilobase mRNA in a number of fetal and adult human tissues and cell lines. The highest levels of its mRNA were detected in fetal brain and in adult heart tissue. The identification of SH-PTP2 along with PTP1C and corkscrew protein suggest that there exist a family of nonreceptor PTP containing SH2-domain which will participate in specific signal transduction pathways involving tyrosine phosphorylation-dephosphorylation.
一个编码非受体蛋白酪氨酸磷酸酶（PTP）的人cDNA克隆已被分离并测序。这个2.1千碱基对的cDNA编码一个593个氨基酸的蛋白质，该蛋白质在C末端含有一个单一的酪氨酸磷酸酶催化结构域。在N末端，该蛋白质有两个相邻的Src同源区域拷贝（SH2结构域），它们在氨基酸水平上分别与人PTP1C的SH2结构域和果蝇螺旋蛋白的SH2结构域有61%和73%的同一性。SH-PTP2与PTP1C或螺旋蛋白之间的总体同源性为58%。当这种蛋白质（或其催化结构域）作为谷胱甘肽-S-转移酶融合蛋白在大肠杆菌中表达时，在细菌细胞提取物中检测到了酪氨酸磷酸酶活性。在PTP催化结构域高度保守的VHCXAGXXR序列中，将保守的半胱氨酸（459）残基定点突变为丝氨酸，导致酶活性完全丧失，证明了这个半胱氨酸残基在催化中的重要性。Northern印迹分析表明，SH-PTP2在许多胎儿和成人的组织及细胞系中作为一种6.5千碱基的mRNA表达。在胎儿脑和成人心脏组织中检测到其mRNA的最高水平。SH-PTP2与PTP1C和螺旋蛋白的鉴定表明，存在一个包含SH2结构域的非受体PTP家族，它们将参与涉及酪氨酸磷酸化-去磷酸化的特定信号转导途径。
