Expression of human tyrosine kinase, Lck, in yeast Saccharomyces cerevisiae: growth suppression and strategy for inhibitor screening.

We report the successful expression and detection of a phosphorylated form of human T cell tyrosine kinase, Lck, in Saccharomyes cerevisiae, which leads to growth suppression of the yeast cells. Expression of an inactive Lck mutant resulted in no phosphorylation and no growth suppression, indicating that cell growth inhibition by Lck is due to the activity of the kinase, consistent with the observed tyrosine-phosphorylation of the Lck and yeast host cell proteins. The addition of a known inhibitor of Lck to the cell culture resulted in recovery of cell growth expressing the active Lck, suggesting that the growth inhibition by lck gene expression can be used to screen inhibitors for the gene product.

Human T-cell leukemia virus type 1 Tax oncoprotein induces and interacts with a multi-PDZ domain protein, MAGI-3.

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL), whereas the closely related virus HTLV-2 has not been associated with such malignant conditions. HTLV-1 Tax1 oncoprotein transforms a rat fibroblast cell line (Rat-1) much more efficiently than does HTLV-2 Tax2. By using a differential display analysis, we isolated MAGI-3 as a Tax1-inducible gene in Rat-1 cells.