title: The synthesis of chloroplast high-molecular-weight ribosomal ribonucleic acid in spinach.
abstract: Illuminated suspensions of chloroplasts isolated from young spinach leaves show incorporation of [3H]uridine into several species of RNA. One such RNA species of Mr 2.7 x 10(6) shows sequence homology with both the chloroplast 23-S rRNA (Mr = 1.05 x 10(6)) and 16-S rRNA (Mr = 0.56 x 10(6)), as judged by DNA/RNA competition hybridization. Leaves labelled in vivo with [32P]orthophosphate in the presence of chloramphenicol accumulate labelled RNAs of Mr 1.28 x 10(6), 0.71/0.75 x 10(6) and 0.47 x 10(6). The 1.28 x 10(6)-Mr RNA shows 80.5% sequence homology with the 1.05 x 10(6)-Mr rRNA and the 0.71/0.75 x 10(6)-Mr RNA mixture shows 76% sequence homology with the 0.56 x 10(6)-Mr rRNA. We conclude that the pathway of rRNA maturation in spinach chloroplasts is similar to that of Escherichia coli.
mesh_terms: D002701:Chloramphenicol / Q000494:pharmacology; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D010944:Plants; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D012335:RNA, Ribosomal; D002701:Chloramphenicol