Honda R, Ohba Y, Yasuda H
Division of Biology, Faculty of Pharmaceutical Sciences, Kanazawa University, Ishikawa, Japan.
Biochem Biophys Res Commun. 1992 Aug 14;186(3):1333-8. doi: 10.1016/s0006-291x(05)81552-9.
The human weel protein, a homologue of the yeast weel protein, was expressed in E. coli and purified to homogeneity. The purified weel protein phosphorylated the tyrosine residue of cdc2 kinase in HeLa cell extracts in the presence of human cyclin B1. It also phosphorylated the tyrosine but not the threonine residue in the peptide of the amino-terminal of cdc2 kinase, although both these residues have been shown to be phosphorylated in higher eukaryotes in vivo. Furthermore, serine and tyrosine residues of the yeast weel protein are reportedly autophosphorylated in vitro, however the tyrosine residue of the human weel protein was autophosphorylated whereas the serine and threonine residues were not. These data indicate that human p50weel is tyrosine kinase and that it phosphorylated the tyrosine residue of the amino-terminal of cdc2 kinase in the presence of cyclin B1 and that the threonine residue is phosphorylated by another, unknown kinase.
人源Wee1蛋白是酵母Wee1蛋白的同源物，在大肠杆菌中表达并纯化至均一。纯化后的Wee1蛋白在人细胞周期蛋白B1存在的情况下，能使HeLa细胞提取物中的cdc2激酶的酪氨酸残基磷酸化。它还能使cdc2激酶氨基末端肽段中的酪氨酸而非苏氨酸残基磷酸化，尽管在高等真核生物体内这两个残基都已被证明会被磷酸化。此外，据报道酵母Wee1蛋白的丝氨酸和酪氨酸残基在体外会发生自身磷酸化，然而人源Wee1蛋白的酪氨酸残基会发生自身磷酸化，而丝氨酸和苏氨酸残基则不会。这些数据表明人源p50Wee1是一种酪氨酸激酶，并且在细胞周期蛋白B1存在的情况下，它会使cdc2激酶氨基末端的酪氨酸残基磷酸化，而苏氨酸残基则由另一种未知激酶磷酸化。
