title: Specific RNA-cleaving activities from HeLa cells.
abstract: Subcellular fractionation of HeLa cells was carried out under gentle conditions to isolate enzymes that cleave RNA precursors in a specific manner. Four separate activities--cleavage of HeLa cell heterogeneous nuclear RNA, the HeLa cell 45S rRNA precursor, RNA . DNA hybrids (RNase H), and the Escherichia coli tRNATyr precursor (RNase P)--were revealed by these studies. The specificity and limited nature of these cleavages suggest that they are due to eukaryotic RNA-processing enzymes. The virtual absence of random nucleases from these enzymes was demonstrated by their inability to cleave the 8000-base early mRNA precursor of bacteriophage T7, E. coli 30S rRNA precursor, or HeLa cytoplasmic poly(A)-containing RNA.
mesh_terms: D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D006367:HeLa Cells / Q000201:enzymology*; D006801:Humans; D008970:Molecular Weight; D009694:Nucleic Acid Precursors / Q000378:metabolism; D012332:RNA, Heterogeneous Nuclear / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D009694:Nucleic Acid Precursors; D012332:RNA, Heterogeneous Nuclear; D012335:RNA, Ribosomal; D012343:RNA, Transfer; D012260:Ribonucleases