Figure 2From: Osmotic stress-dependent serine phosphorylation of the histidine kinase homologue DokAIn vivo phosphorylation of DokA during osmotic stress. PHKR was immunoprecipitated from the cell lysate of radioactively labeled and osmotically shocked Dictyostelium PHKR cells. Purified proteins were separated by SDS-PAGE, blotted onto a PVDF membrane and subjected to autoradiography. Panel A: PHKR is phosphorylated in vivo during osmotic shock (t = 20 min, 40 min). Mutation of the conserved histidine in PHKR does not affect the phosphorylation of PHKR. Before the osmotic shock (t = 0 min), neither of the two DokA fragments are phosphorylated. The radioactive label can not be removed by treating the membrane with 1 N HCl for 1 h. It was shown by immunostaining with the mAb 426/HK antibody that equal amounts of protein were purified at each point in time. Panel B: PHKR precipitated from untreated cells is not radioactively labeled.Back to article page