Distribution of the early light‐inducible protein in the thylakoids of developing pea chloroplasts

Abstract

The distribution of the early light‐inducible protein (ELIP) of pea ( Pisum sativum ) between grana and stroma thylakoids was studied. An antibody raised against a bacterial‐expressed fusion protein containing ELIP sequences was used. Illumination of dark‐grown pea seedlings causes an accumulation of the ELIP in the thylakoid membranes with a maximum level at 16 h. During continuous illumination exceeding 16 h the level decreases again. The fractionation of thylakoid membranes of 48‐h‐illuminated pea seedlings in grana and stroma thylakoids reveals that there is no uniform distribution of ELIP in the thylakoids. Rather 60–70% of ELIP was found in the stroma thylakoids and 30–40% in the grana thylakoids. This distribution is in accordance with that of photosystem I but not with that of photosystem II. After Triton‐X‐100 solubilization almost all ELIP is found in the photosystem‐I‐containing fraction. This also supports an association of ELIP with photosystem I.