title: Study of the type of RNA, degraded by polynucleotide phosphorylase in polyribosomal fraction of rat liver.
abstract: The type of RNA is studied, which is degraded by polynucleotide phosphorylase (PNPase) in the fraction of free ribosomes and ribosomes released from endoplasmic reticulum membranes with Triton X-100. Beta-32P labelled ADP, UDP, GDP and CDP are found among the degradation products of endogenous RNA of free and bound ribosomes in vitro in the presence of 32P-ortophosphate. An analysis of molar ratio of beta-32P-NDP isolated revealed that PNPase degrades RNA of GC type in both ribosome  fractions. The amount of PNPase-degraded RNA in bound ribosimes is 4-fold as high as that in free ribosomes under the same conditions. Analysis of stable 32P-RNA and rapidly labelled 32-P-dRNA, isolated from bound ribosomes after the incubation with and without inorganic phosphate, revealed that PNPase attacks the 28S fragment of RNA, which consists of about 370 nucleotides, and dRNA having a sedimentation coefficient less than 12S. The rate of dRNA degradation is considerably higher than that of rRNA. 5'-RNAase, hydrolysing synthetic homopolyribonucleotides to oligonucleotides with free 3'-OH terminal group, apparently participates, together with PNPase, in dRNA and rRNA degradation.
mesh_terms: D000818:Animals; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D011092:Polyethylene Glycols; D011117:Polyribonucleotide Nucleotidyltransferase; D011132:Polyribosomes / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D051381:Rats; D012265:Ribonucleotides / Q000032:analysis
chemical_list: D012335:RNA, Ribosomal; D012265:Ribonucleotides; D011092:Polyethylene Glycols; D011117:Polyribonucleotide Nucleotidyltransferase
vernacular_title: Issledovanie tipa RNA, razrushaemoĭ polinukleotidfosforilazoĭ v sostave poliribosomnoĭ fraktsii perceni krysy