RNase activity in erythroid cell lysates.
The characteristics of degradation of reticulocyte ribonucleic acid (RNA) and ribosomes were studied in a whole erythroid cell lysate system. The process followed Michaelis-Menten kinetics, and indicated that RNA degradation in the erythroid cell is mediated by an enzyme previously isolated from reticulocyte hemolysates. Erythroid cell RNase activity had a temperature optimum of 50 degrees C, a pH optimum of 7.0, was not energy dependent, was heat labile at physiologic pH, and was inhibited by Mg(++), Ca(++), and exposure to bentonite and deoxycholate. Free sulfhydryl groups were not essential for RNase activity. Of the substrates occurring naturally within the erythroid cell, isolated ribosomal RNA was most susceptible to the action of the enzyme, intact ribosomes least susceptible, and transfer RNA intermediate between them. Natural substrates were degraded completely to nucleotides in cell lysates. Competitive inhibition studies indicate that one enzyme system is capable of degrading both RNA and ribosomes, although the existence of more than one enzyme has not been excluded. Erythroid cell lysates quickly broke down polyribosomes into single ribosomes. The more rapid degradation of ribosomes, as compared with transfer RNA, which occurs in vivo, as opposed to findings in vitro, suggests that there is a special intracellular mechanism responsible for ribosome degradation in the maturing erythroid cell.
D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D010759:Phosphorus Isotopes; D012313:RNA / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000187:drug effects / Q000201:enzymology*; D012260:Ribonucleases; D012270:Ribosomes; D013438:Sulfhydryl Compounds; D013696:Temperature
D000963:Antimetabolites; D007477:Ions; D010759:Phosphorus Isotopes; D013438:Sulfhydryl Compounds; D012313:RNA; D012260:Ribonucleases
Science. 1968 Dec 13;162(3859):1287
5699205
Proc Natl Acad Sci U S A. 1962 Dec;48(12):2163-71
16591030
Proc Natl Acad Sci U S A. 1963 Jul;50:134-40
13949910
J Lab Clin Med. 1966 Nov;68(5):833-7
5923899
Hoppe Seylers Z Physiol Chem. 1967 Jul;348(7):817-22
4873915
Virology. 1961 May;14:54-8
13701154
Biochim Biophys Acta. 1964 Oct 23;92:59-70
14243789
Biochim Biophys Acta. 1964 Dec 16;91:606-11
14262447
J Surg Res. 1968 Nov;8(11):551-4
5687387
Blood. 1960 Jan;15:71-81
13792723
J Clin Invest. 1964 Jul;43:1329-37
14192513
J Mol Biol. 1964 Jul;9:154-67
14200379
J Biol Chem. 1967 Apr 10;242(7):1533-40
6023221
Proc Natl Acad Sci U S A. 1963 Jan 15;49:122-9
13998950
Folia Haematol Int Mag Klin Morphol Blutforsch. 1956;74(3):251-7
13397581
J Biol Chem. 1968 Jul 10;243(13):3573-80
4968798
Biochim Biophys Acta. 1968 Oct 29;166(3):672-80
5722697
J Biol Chem. 1968 Dec 25;243(24):6464-73
5726896