CHLOROPLAST IMPORT OF THE PRECURSOR OF THE GAMMA SUBUNIT OF PEA CHLOROPLAST ATP SYNTHASE

A cDNA clone encoding the complete precursor of the gamma subunit of the pea chloroplast ATP synthase has been isolated from a pea leaf cDNA library in lambdagt11 following detection with antibodies to the purified gamma subunit. The cDNA insert of 1.4 kbp is smaller than transcripts of about 1.6 kb detected by northern hybridisation of RNA from both light- and darkgrown pea leaves. The cDNA encodes a polypeptide of 376 amino acid residues, of which 52 residues constitute an N-terminal presequence and 324 residues make up the mature protein. Transcription and translation of the cDNA in vitro produced a protein of 42 kDa, which was imported by isolated pea chloroplasts and processed to the mature 36 kDa subunit.