Lifetimes of photosystem I and II proteins in the cyanobacterium Synechocystis sp. PCC 6803 (original) (raw)

The half‐life times of photosystem I and II proteins were determined using 15N‐labeling and mass spectrometry. The half‐life times (30–75 h for photosystem I components and <1–11 h for the large photosystem II proteins) were similar when proteins were isolated from monomeric vs. oligomeric complexes on Blue‐Native gels, suggesting that the two forms of both photosystems can interchange on a timescale of <1 h or that only one form of each photosystem exists in thylakoids in vivo. The half‐life times of proteins associated with either photosystem generally were unaffected by the absence of Small Cab‐like proteins.