Park W Y, Seo J S
Transgenic Mice Center, Cancer Research Institute, Seoul, Korea.
Biochem Biophys Res Commun. 1995 Jun 15;211(2):447-53. doi: 10.1006/bbrc.1995.1834.
P130gag-fps, the product of Fujinami sarcoma virus, has a leucine zipper (LZ) motif located in 729-756 amino acid residues. To explore the role of LZ-like domain in the transformation by P130gag-fps, we made a deletion (delta FpsLZ/SH2) and a site-directed substitution mutation (L746P). Deletion mutant did not transform the 3Y1 cells and the resulting protein did not show kinase activity. Substitution of Leu746 with Pro (L746P) reduced the transforming activity by 6-fold. Although the L746P mutant retained intact catalytic activity in vitro, it did not phosphorylate cellular proteins in vivo. We concluded that LZ-like domain might mediate the trans-activation of P130gag-fps tyrosine kinase by autophosphorylation, which is prerequisite for the transforming activity.
P130gag-fps是藤浪肉瘤病毒的产物，在其729 - 756个氨基酸残基处有一个亮氨酸拉链（LZ）基序。为了探究类LZ结构域在P130gag-fps转化过程中的作用，我们构建了一个缺失突变体（delta FpsLZ/SH2）和一个定点取代突变体（L746P）。缺失突变体不能转化3Y1细胞，产生的蛋白质也不显示激酶活性。将亮氨酸746替换为脯氨酸（L746P）使转化活性降低了6倍。尽管L746P突变体在体外保留了完整的催化活性，但它在体内不能磷酸化细胞蛋白。我们得出结论，类LZ结构域可能通过自身磷酸化介导P130gag-fps酪氨酸激酶的反式激活，这是转化活性的先决条件。
