Figure 3.

A strain lacking NBP2 has increased basal Hog1 kinase activity and a defect in adaptation. (A) Hog1 kinase activity was examined prior to and following stress in the NBP2 wild-type (IMY100) and in the nbp2Δ (JHM29) strains each carrying the Hog1-HA expression plasmid pHOG1-ha2 (Warmka et al, 2001). Before (time 0) and after exposure to osmotic stress (0.4M NaCl) for various times, Hog1-HA was immunoprecipitated and incubated with MBP and [γ-³²P]ATP. Radiolabel incorporated into MBP was examined by SDS–PAGE and visualized using the PhosphorImager. Hog1-HA expression was the same in the two strains and unaltered by stress as indicated by the anti-HA blots of the lysates. (B) Hog1 kinase assays performed as in (A), for wild type (triangles) and nbp2Δ (circles) from three independent experiments. The plot shows the mean±s.d.