Inhibition of proton pumping in corn roots is associated with increased phosphorylation of membrane proteins

Brief cold shock given to corn root tissue which has been preloaded with 32P-labeled phosphate increases the phosphorylation of microsomal membrane proteins. Gel electrophoresis shows that discrete proteins are labeled. Preincubation of sealed microsomal vesicles under conditions producing membrane protein phosphorylation causes a 25% loss of total ATPase activity and 55% loss of uncoupler-sensitive activity. It is believed that the effect of injury or shock in blocking H+ efflux pumping by corn roots may be attributed to phosphorylation of the H+-ATPase. Calcium influx attending injury may be responsible for activating the protein kinase.