Regulation of proton flow and ATP synthesis in chloroplasts

The chloroplast ATP synthase is strictly regulated so that it is very activ e in the light (rates of ATP synthesis can be higher than 5 mu mol/min/mg p rotein), but virtually inactive in the dark. The subunits of the catalytic portion of the ATP synthase involved in activation, as well as the effects of nucleotides are discussed. The relation of activation to proton flux thr ough the ATP synthase and to changes in the structure of enzyme induced by the proton electrochemical gradient are also presented. It is concluded tha t the gamma and epsilon subunits of CF1 play key roles in both regulation o f activity and proton translocation.