title: A 5' exoribonuclease from cytoplasmic extracts of mouse sarcoma 180 ascites cells.
abstract: An exonuclease that appears to represent the predominant nuclease activity in cytoplasmic extracts of sarcoma 180 ascites cells has been partially purified and characterized. The enzyme attacks RNA chains in a 5' to 3' direction, and releases 5'-mononucleotides. The initial cleavage, however, can occur at either the first, second and probably third phosphodiester linkage in some RNAs. The enzyme attacks transcripts terminated with a 5'-triphosphate more slowly than those with a 5' monophosphate, and releases a compound larger than GTP from transcripts that begin with a pppG. Capped transcripts are cleaved at least as readily as those with a 5'-P, yielding a compound larger than 7mGpppGm. The occurrence of an such an exonuclease capable of attacking capped RNAs would make it possible for mammalian cells to initiate mRNA degradation by a 5' exonucleolytic mechanism.
authors: Department of Biochemistry, Tufts University Health Sciences Schools, Boston, MA 02111.
authors: M
authors: M
authors: Coutts
authors: G
authors: G
authors: Brawerman
mesh_terms: D000818:Animals; D003568:Cytidine Monophosphate / Q000378:metabolism; D003570:Cytidine Triphosphate / Q000378:metabolism; D003593:Cytoplasm / Q000201:enzymology; D005095:Exoribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D010761:Phosphorus Radioisotopes; D012510:Sarcoma 180 / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010761:Phosphorus Radioisotopes; D003570:Cytidine Triphosphate; D005095:Exoribonucleases; C028793:5'-exoribonuclease; D003568:Cytidine Monophosphate