Cloning and Sequence Analysis of the Human Mitochondrial Translational Initiation Factor 2 cDNA

doi:10.1074/jbc.270.4.1859

Cloning and Sequence Analysis of the Human Mitochondrial Translational Initiation Factor 2 cDNA (*)

Lan Ma(1) and
Linda L. Spremulli(1)(2)

From the (1)Department of Chemistry and
(2)Lineberger Comprehensive Cancer Research Center, University of North Carolina, Chapel Hill, North Carolina 27599

Abstract

Complete cDNAs encoding human mitochondrial translational initiation factor 2 (IF-2) 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-2 has 30-40% identity to the corresponding prokaryotic factors. Surprisingly, it is no more homologous to yeast IF-2 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-2 mRNA. Northern analysis indicates that the IF-2 gene is expressed in all tissues but that the level of expression varies over a wide range.

Footnotes

↵* This work is supported in part by funds provided by National Institutes of Health Grant GM32734. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank_(TM)/EMBL Data Bank with accession number(s) L34600[GenBank].
↵¹ The abbreviations used are:

IF-2

initiation factor 2

IF-2

mitochondrial translational initiation factor 2

PCR

polymerase chain reaction

kb

kilobase(s)

bp

base pair(s)

UTL

untranslated leader

eIF-2

eukaryotic cytoplasmic initiation factor 2

uORF

upstream open reading frame.
↵² M. Farwell, J. Ma, W. Burkhart, and L. Spremulli, unpublished observations.
- Received July 25, 1994.
- Revision received November 18, 1994.