title: In vitrocleavage of 45S pre-ribosomal RNA and of giant heterogeneous RNA extracted from human leukemic cells.
abstract: 45S ribosomal precursor RNA and large heterogeneous RNA molecules (greater than 45S) extracted from human leukemic cells were incubated in vitro with purified RNase III, which specifically attacks double-helical RNA regions. About 50% of the ribosomal precursor was cleaved into two major fragments sedimenting at 28S and 32S respectively. A limited number of cleavages was also introduced in about 40% of heterogeneous RNA molecules sedimenting faster than 45S, causing a partial 'shift' to a polydisperse distribution in the 10S-45S range.
mesh_terms: D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D006801:Humans; D007938:Leukemia / Q000032:analysis*; D012313:RNA / Q000032:analysis*; D012335:RNA, Ribosomal / Q000032:analysis; D012260:Ribonucleases / Q000378:metabolism*
chemical_list: D012335:RNA, Ribosomal; D012313:RNA; D012260:Ribonucleases