title: Direct association of messenger RNA-containing ribonucleoprotein particles with membranes of the endoplasmic reticulum in ethionine-treated rat liver.
abstract: The administration of ethionine to female rats causes breakdown of hepatic polysomes. The fate of the mRNA molecules after polysome breakdown was investigated by measuring the amount of poly(A)-containing mRNA in membranous and non-membranous fractions obtained from the cytoplasm of ethionine-treated rat liver. The amount of poly(A)-containing mRNA in the membrane fraction of ethionine-treated liver was found to be the same as that of normal liver. When poly(A)-containing mRNAs from various fractions were translated in a wheat germ system and the products were isolated by immunoprecipitation, the albumin-specific mRNA was found exclusively in the membrane fraction of both normal and ethionine-treated livers. The membrane-bound mRNA in ethionine-treated liver, selectively labeled with [14C]orotate, was banded in CsCl gradient centrifugation at 1.42 g/ml which corresponds to the previously reported mRNA-containing ribonucleoprotein particles. From these results, we concluded that even after the polysome disaggregation by ethionine, most of the mRNA of membrane-bound polysomes remains attached to the endoplasmic reticulum membranes independently of ribosomes and the nascent polypeptide chains.
mesh_terms: D000818:Animals; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005001:Ethionine / Q000494:pharmacology*; D005260:Female; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D009698:Nucleoproteins / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012261:Ribonucleoproteins / Q000378:metabolism*
chemical_list: D009698:Nucleoproteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D011061:Poly A; D005001:Ethionine