MOLECULAR-CLONING OF A CHLOROPLASTIC PROTEIN ASSOCIATED WITH BOTH THEENVELOPE AND THYLAKOID MEMBRANES

Chloroplasts consist of six morphologically distinct compartments. Eac h compartment has a specific set of polypeptides that perform distinct biochemical functions. We report here the identification of a membran e-associated protein with a novel localization. This protein was synth esized as a 37 kDa precursor and was processed to a mature protein of 30 kDa after being imported into isolated pea chloroplasts. Fractionat ion of chloroplasts showed that the 30 kDa mature protein was associat ed with both of the envelope membranes as well as with thylakoid membr anes. Immunocyto-chemical localization of the 30 kDa protein revealed that the protein occurred in clusters in the vicinity of both the enve lope and the thylalkoid. Possible functions of this 30 kDa protein, in ferred from its novel localization pattern, are discussed.