title: The binding sites for tRNA on eukaryotic ribosomes.
abstract: We have studied the non-enzymic binding of phe-tRNA to ribosomes from rat liver using deacylated tRNA to inhibit binding to the P-site and puromycin (5 x 10-minus3M) to inhibit binding to the A-site. We conclude that at a low concentration of magnesium ions (10mM) phe-tRNA is bound only at the A-site of 80S irbosomes, whereas at a high concentration of magnesium ions (40mM) phe-tRNA is also bound at the P-site. Studies with edeine indicate that, during non-enzymic binding of phe-tRNA, eukaryotic ribosomes (in contrast to prokarotic ribosomes) have the A-site of the 60S subunit and the initiation site of the 40S subunit juxtaposed. This may account for the differences observed, in formation of diphenylalanyl-tRNA and phenylalanyl-puromycin, between phe-tRNA bound non-enzymically to the P-sites of eukaryotic and prokaryotic ribosomes.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002854:Chromatography, Paper; D004486:Edeine / Q000494:pharmacology; D004926:Escherichia coli; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D010649:Phenylalanine / Q000378:metabolism; D011691:Puromycin / Q000494:pharmacology; D012343:RNA, Transfer / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D014462:Ultrafiltration
chemical_list: D004486:Edeine; D010649:Phenylalanine; D011691:Puromycin; D012343:RNA, Transfer; D008274:Magnesium