Abstract
Complete cDNAs encoding human mitochondrial translational initiation factor 2 (IF-2mt) have been obtained from liver, heart, and fetal brain cDNA libraries. These cDNAs have a long open reading frame 2181 residues in length encoding a protein of 727 amino acids. Overall, human IF-2mt has 30-40% identity to the corresponding prokaryotic factors. Surprisingly, it is no more homologous to yeast IF-2mt than to the IF-2s from bacterial sources. The greatest region of conservation lies in the G-domain of this factor with less conservation in the COOH-terminal half of the protein and very little homology near the amino terminus. The 5'-untranslated leaders of the liver and heart cDNAs contain a number of short open reading frames. These sequences may play a role in the translational activity of the IF-2mt mRNA. Northern analysis indicates that the IF-2mt gene is expressed in all tissues but that the level of expression varies over a wide range.
Highlights
From the tDepartment of Chemistry and §Lineberger Comprehensive Cancer Research Center, University of North Carolina, Chapel Hill, North Carolina 27599
IF-2rn t promotes the binding of tMettRNA to animal mitochondrial ribosomes in a GTP- and mRNA-dependent reaction
Polymerase Chain Reaction-Highly conserved peptide sequences found in the G-domains of prokaryotic and mitochondrial IF-2s served as the basis for designing primers for cDNA synthesis and the polymerase chain reaction (PCR)
Summary
(Received for publication, July 25, 1994, and in revised form, November 18, 1994). From the tDepartment of Chemistry and §Lineberger Comprehensive Cancer Research Center, University of North Carolina, Chapel Hill, North Carolina 27599. Complete cDNAs encoding human mitochondrial translational initiation factor 2 (IF-2m t ) have been obtained from liver, heart, and fetal brain cDNA libraries These cDNAs have a long open reading frame 2181 residues in length encoding a protein of 727 amino acids. Prokaryotic initiation factor 2 (IF_2) is a single polypeptide chain having a molecular weight of 78,000-97,000 It promotes tMet-tRNA binding to 30 S ribosomal subunits in a mRNA-dependent reaction. Eukaryotic cytoplasmic initiation factor 2 (eIF-2) is a trimeric protein with a molecular weight of 145,000 (3) It is responsible for the binding of Met-tRNA to 40 S subunits. IF-2rn t in yeast has not been purified or characterized, its gene has been cloned (19), The sequence of this factor suggests that it has significant homology to bacterial IF-2 except near the amino terminus. We have cloned and characterized the cDNAs for IF-2rn t from human liver, heart, and fetal brain
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
