title: Modifications of 60 S ribosomal subunits induced by the ricin A chain.
abstract: Incubation of 60 S ribosomal subunits with the ricin A chain reduced their stability during heat treatment. The toxin shifted the thermal denaturation curve of the subunits towards lower temperatures, in a similar way to that produced by the decrease in Mg2+ concentration. A brief heating (3 min at 57 degrees C), which did not affect control subunit activity, enhanced protein synthesis inhibition of the toxin-treated subunits that released more 5 S RNA, in the form of nucleoprotein complex(es) with protein L5 and phosphoproteins P1P2 (RNPH), than did heated control subunits [(1984) Eur. J. Biochem. 143, 303-307]. No nuclease activity tested on 60 S subunits and purified 5 S and 5.8 S RNA was found associated with the toxin. The results suggest that the toxin induced a limited conformational change of the 60 S subunit, which destabilized the interaction between RNPH and the rest of the subunit.
mesh_terms: D000818:Animals; D006358:Hot Temperature; D008099:Liver / Q000648:ultrastructure; D008274:Magnesium / Q000494:pharmacology; D014176:Protein Biosynthesis; D012335:RNA, Ribosomal / Q000378:metabolism; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D012276:Ricin / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D012335:RNA, Ribosomal; D012261:Ribonucleoproteins; D012276:Ricin; D012260:Ribonucleases; D008274:Magnesium