Involved in translation and accumulation of chloroplast ATP synthase subunits. Interacts with the 5'-UTR of the chloroplast bicistronic atpB and atpE mRNA and activates its translation by facilitating ribosome association with the mRNA (PubMed:22708543). Required for accumulation and activity of the chloroplast ATP synthase. Enhances atpA translation and is required for accumulation of specific processed atpF and psaJ transcripts (PubMed:22708543, PubMed:23735295). Required for the stabilization of bicistronic rpl16 and rpl14 mRNAs (PubMed:23735295). Pale green leaf phenotype. Belongs to the PPR family. P subfamily.