Although the 32 kOa-polypeptide (0-1) is a minor component of thyla- koids in algae and higher plants. much attention has been focused on it. It was shown to be the binding site for herbicides (Pfister et al. 1981). the rapidly synthesized polypeptide of thylakoid membranes (Edelman and Reisfeld 1978; Owens et al. 1982) and to participate in Qa binding (Arntzen et al. 1984; Kyle et al. 1984; Ohad et al. 1984). Measurements of the stoichiometry of the various PS II polypeptides in C. reinhardii showed that thylakoids contain about one herbicide binding polypeptide per one PS II unit and the...