Modesti A, Bini L, Carraresi L, Magherini F, Liberatori S, Pallini V, Manao G, Pinna L A, Raugei G, Ramponi G
Dipartimento di Scienze Biochemiche, Università di Firenze, Italy.
Electrophoresis. 2001 Feb;22(3):576-85. doi: 10.1002/1522-2683(200102)22:3<576::AID-ELPS576>3.0.CO;2-P.
Small tyrosine phoshatase 1 (Stp1) is a Schizosaccharomyces pombe low-molecular-mass phosphotyrosine-phosphatase 50% identical to Saccharomyces cerevisiae Ltp1. In order to investigate the role of Stp1 in yeast, a mutant was generated having the characteristic of a dominant negative molecule. Changes in protein tyrosine phosphorylation in S. cerevisiae proteome in response to Stp1 or its dominant negative mutant expression were analyzed by high-resolution two-dimensional (2-D) electrophoresis. The most remarkable result is the modification by phosphorylation on tyrosine of several proteins involved in carbohydrate metabolism. Twelve proteins were identified on the basis of their positions in the anti-phosphotyrosine immunoblot of the 2-D electrophoresis. Ten of these present tyrosyl residues that are within the consensus sequence for protein kinase CK2 (casein kinase-2). These data open the possibility for the identification of Stp1 substrates in yeast and provide hints about the nature of tyrosine phosphorylating agents in yeast and in other organisms where bona fide tyrosine kinases are lacking.
小酪氨酸磷酸酶1（Stp1）是粟酒裂殖酵母中的一种低分子量磷酸酪氨酸磷酸酶，与酿酒酵母Ltp1有50%的同源性。为了研究Stp1在酵母中的作用，构建了一个具有显性负性分子特征的突变体。通过高分辨率二维（2-D）电泳分析了酿酒酵母蛋白质组中响应Stp1或其显性负性突变体表达时蛋白质酪氨酸磷酸化的变化。最显著的结果是参与碳水化合物代谢的几种蛋白质的酪氨酸磷酸化修饰。根据它们在二维电泳的抗磷酸酪氨酸免疫印迹中的位置鉴定出了12种蛋白质。其中10种蛋白质的酪氨酰残基位于蛋白激酶CK2（酪蛋白激酶2）的共有序列内。这些数据为鉴定酵母中的Stp1底物提供了可能性，并为酵母以及缺乏真正酪氨酸激酶的其他生物体中酪氨酸磷酸化剂的性质提供了线索。
