Shin D Y, Ishibashi T, Choi T S, Chung E, Chung I Y, Aaronson S A, Bottaro D P
Laboratory of Cellular and Molecular Biology, Division of Basic Science, National Cancer Institute, Bethesda, Maryland 20892, USA.
Oncogene. 1997 Jun 5;14(22):2633-9. doi: 10.1038/sj.onc.1201106.
A cDNA encoding a novel human extracellularly-regulated kinase (ERK) phosphatase, designated B59, was isolated from a B5/589 human mammary epithelial cell cDNA library. The 1104 nucleotide open reading frame encodes 368 amino acids including the highly conserved catalytic site sequence of protein phosphotyrosine phosphatases (PTPs), VXVHCXXGXXR, at amino acid position 276-287. The predicted 70 amino acid stretch surrounding the HC motif shares significant sequence identity with other human dual specificity PTPs (dsPTPs), including the known ERK PTPs CL100, PAC1, B23, as well as the dsPTPs VH-1 and VHR. B59 protein synthesized in vitro in a rabbit reticulocyte lysate dephosphorylated rat ERK1 and ERK2 proteins whose phosphorylation had been stimulated by v-mos kinase added to the lysate. Ectopic expression of B59 in NIH3T3 fibroblasts inhibited the induction of an oncogene-responsive promoter by the dominant-activating raf mutant, raf-BXB. Moreover, cotransfection of NIH3T3 cells with B59 inhibited morphological transformation by H-ras and v-raf oncogenes. These results suggest that B59 suppresses the transforming activity of H-ras or v-raf oncogenes through ERK dephosphorylation and inactivation.
从人B5/589乳腺上皮细胞cDNA文库中分离出一种编码新型人细胞外调节激酶（ERK）磷酸酶的cDNA，命名为B59。1104个核苷酸的开放阅读框编码368个氨基酸，其中在氨基酸位置276 - 287处包含蛋白酪氨酸磷酸酶（PTP）高度保守的催化位点序列VXVHCXXGXXR。围绕HC基序预测的70个氨基酸片段与其他人类双特异性PTP（dsPTP）具有显著的序列同一性，包括已知的ERK PTPs CL100、PAC1、B23，以及dsPTPs VH - 1和VHR。在兔网织红细胞裂解物中体外合成的B59蛋白使添加到裂解物中的v - mos激酶刺激磷酸化的大鼠ERK1和ERK2蛋白去磷酸化。B59在NIH3T3成纤维细胞中的异位表达抑制了显性激活的raf突变体raf - BXB对癌基因反应性启动子的诱导。此外，NIH3T3细胞与B59共转染抑制了H - ras和v - raf癌基因引起的形态转化。这些结果表明，B59通过ERK去磷酸化和失活来抑制H - ras或v - raf癌基因的转化活性。
