James P, Hall B D, Whelen S, Craig E A
Department of Genetics, University of Washington, Seattle 98195.
Gene. 1992 Dec 1;122(1):101-10. doi: 10.1016/0378-1119(92)90037-p.
In higher eukaryotic organisms, the regulation of tyrosine phosphorylation is known to play a major role in the control of cell division. Recently, a wide variety of protein tyrosine phosphatase (PTPase)-encoding genes (PTPs) have been identified to accompany the many tyrosine kinases previously studied. However, in the yeasts, where the cell cycle has been most extensively studied, identification of the genes involved in the direct regulation of tyrosine phosphorylation has been difficult. We have identified a pair of genes in the yeast Saccharomyces cerevisiae, which we call PTP1 and PTP2, whose products are highly homologous to PTPases identified in other systems. Both genes are poorly expressed, and contain sequence elements consistent with low-abundance proteins. We have carried out an extensive genetic analysis of PTP1 and PTP2, and found that they are not essential either singly or in combination. Neither deletion nor overexpression results in any strong phenotypes in a number of assays. Deletions also do not affect the mitotic blockage caused by deletion of the MIH1 gene (encoding a positive regulator of mitosis) and induction of the heterologous Schizosaccharomyces pombe wee1+ gene (encoding a negative regulator of mitosis). Molecular analysis has shown that PTP1 and PTP2 are quite different structurally and are not especially well conserved at the amino acid sequence level. Low-stringency Southern blots indicate that yeast may contain a family of PTPase-encoding genes. These results suggest that yeast may contain other PTPase-encoding genes that overlap functionally with PTP1 and PTP2.
在高等真核生物中，已知酪氨酸磷酸化的调节在细胞分裂控制中起主要作用。最近，已鉴定出多种编码蛋白酪氨酸磷酸酶（PTPase）的基因（PTPs），它们伴随着先前研究的许多酪氨酸激酶。然而，在细胞周期研究最为广泛的酵母中，鉴定直接参与酪氨酸磷酸化调节的基因一直很困难。我们在酿酒酵母中鉴定出一对基因，我们将其称为PTP1和PTP2，它们的产物与在其他系统中鉴定出的PTPases高度同源。这两个基因表达水平都很低，并且含有与低丰度蛋白一致的序列元件。我们对PTP1和PTP2进行了广泛的遗传分析，发现它们单独或联合存在时都不是必需的。在许多检测中，缺失或过表达都不会导致任何明显的表型。缺失也不会影响由MIH1基因（编码有丝分裂的正向调节因子）缺失和异源粟酒裂殖酵母wee1 +基因（编码有丝分裂的负向调节因子）诱导所引起的有丝分裂阻滞。分子分析表明，PTP1和PTP2在结构上有很大差异，并且在氨基酸序列水平上保守性不是特别高。低严谨度的Southern杂交表明酵母可能含有一个编码PTPase的基因家族。这些结果表明酵母可能含有其他与PTP1和PTP2功能重叠的编码PTPase的基因。
