title: Identification and initial characterization of translational initiation factor 2 from bovine mitochondria.
abstract: The bovine liver mitochondrial factor that promotes the binding of fMet-tRNA to mitochondrial ribosomes, initiation factor 2 (IF-2mt), has been identified in the postribosomal supernatant fraction of isolated liver mitochondria. This factor has been purified approximately 5,000-fold and present preparations are estimated to be about 10% pure. IF-2mt has an apparent molecular weight of about 140,000 as determined by gel filtration chromatography. IF-2mt is active in stimulating fMet-tRNA binding to Escherichia coli ribosomes but E. coli IF-2 is not active in promoting initiator tRNA binding to animal mitochondrial ribosomes. The IF-2mt-mediated binding of fMet-tRNAi(Met) to mitochondrial ribosomes is dependent on the presence of a message such as poly(A,U,G) and on GTP. Nonhydrolyzable analogs of GTP are 2-3-fold less effective in promoting initiation complex formation on mitochondrial ribosomes than is GTP suggesting that IF-2mt is capable of recycling to some extent under the current assay conditions.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
authors.forename: H X
authors.initials: HX
authors.lastname: Liao
authors.forename: L L
authors.initials: LL
authors.lastname: Spremulli
mesh_terms: D000818:Animals; D002417:Cattle; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D015852:Eukaryotic Initiation Factor-2 / Q000302:isolation & purification* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D015636:Magnesium Chloride / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000378:metabolism*; D011131:Polyribonucleotides / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012358:RNA, Transfer, Met; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D011131:Polyribonucleotides; D012346:RNA, Transfer, Amino Acyl; D012358:RNA, Transfer, Met; C024988:tRNA, formylmethionine-; D015636:Magnesium Chloride; D006165:Guanylyl Imidodiphosphate; D011189:Potassium Chloride; D006160:Guanosine Triphosphate