FIG. 1.

MTK1 N-terminal region inhibits its kinase activity. (A) Yeast strain FP75 (Δssk2 Δssk22 Δste11) was transformed with either a centromeric vector plasmid (p414ADH) or one of its derivatives containing various MTK1 segments. Transformed cells were spread on YPD agar plates supplemented with (+) or without (−) 1.5 M sorbitol. FP75 cells grow on plates containing sorbitol only when the MTK1 kinase activity is expressed. The segment of MTK1 cDNA sequence included in each construct is indicated, both schematically and numerically, in panel B. (B) The topmost bar represents the full-length MTK1 cDNA (amino acids from positions 22 through the C terminus [position 1607]), and other bars represent deletion derivatives. The gray section indicates the GADD45-binding site, whereas the filled section indicates the kinase catalytic domain. Funct. compl., functional complementation; +, complementation; −, no complementation.