Localization of 4S RNA genes on the chloroplast genome of Chlamydomonas reinhardii.

The genes coding for 4S RNA have been localized on the physical map of the chloroplast genome of Chlamydomonas reinhardii by hybridizing 32P-labelled 4S RNA to EcoRI, BamHI, Bg1II and Hind III chloroplast DNA digests and to hybrid plasmids containing EcoRI and Bam HI chloroplast DNA fragments. At least 10 EcoRI and 7 Bam HI fragments carry sequences coding for 4S RNA. These genes are interspersed throughout the genome. The spacer between the 16S and 23S ribosomal RNA genes, which is repeated twice per chloroplast DNA molecule, codes for at least one 4S RNA, shown to be transcribed from the same strand as the ribosomal RNAs.