Biosynthesis and Assembly of Thylakoid Membrane Proteins in Isolated Chloroplasts from Vicia faba L.: The P700-Chlorophyll a-Protein

Isolated Vicia faba chloroplasts were incubated with [ 35 S]methionine in the light, and the newly formed polypeptide products associated with thylakoid membranes were separated by lithium dodecylsulfate polyacrylamide gel electrophoresis (LiDS-PAGE). At least 30 different labeled polypeptides could be distinguished on fluorographs of the gels. Part of them did not comigrate with any stained bands of proteins, but a number of about 15 corresponded in size to preexisting thylakoid components. The inhibition pattern obtained with inhibitors of photophosphorylation (CCCP, DCMU) and translation (cycloheximide, D-threo-chloramphenicol, ribonuclease) indicates that labeling of all these polypeptides occurred in intact chloroplasts only and was energized by photophosphorylation.