A rapidly light‐induced chloroplast protein with a high turnover coded for by pea nuclear DNA

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Abstract
Among the translation products obtained in vitro with mRNA isolated from etiolated grown pea, or after different times of illumination following the etiolation, a 24,000 MW protein was observed in the very early phase of greening; its occurrence culminates at 2-4 h after the start of illumination. The corresponding mRNA appears in and disappears from the poly(A)-containing RNA population within hours. The protein product was characterized as the precursor for a 17,000 MW chloroplast protein; by means of post-translational transport in vitro, the processed product becomes bound to chloroplast membranes. A product of the same size can also be labeled in vivo with a maximum of incorporation of label at 6-8 h after illumination. This product decays with a half-life of about 5 h. These findings imply a regulatory function of the 17,000 MW protein during the process of greening, possibly by synchronization of nuclear and chloroplast genomes. Other possibilities are considered.