Isolation and characterisation of 14-S RNA from spinach chloroplasts

14-S RNA was purified from spinach chloroplasts. It has a molecular weight of 0.43 . 10(6) and the following nucleotide composition: 20% CMP, 23.9% AMP, 24.2% GMP and 31.9% UMP. The accumulation of 14-S RNA in chloroplasts of cotyledons of dark-grown plants is stimulated by light. Conditions are described for the isolation of 14-S RNA in the absence of appreciable fragmentation of chloroplast 23-S rRNA and the evidence that it represents a distinct type of chloroplast RNA is discussed. Translation of 14-S RNA in a protein synthesising system from Escherichia coli gives rise to two polypeptides with molecular weights of 13 200 and 12 600 and the possible role of 14-S RNA as a chloroplast messenger is discussed.