title: The delta-subunit of murine guanine nucleotide exchange factor eIF-2B. Characterization of cDNAs predicts isoforms differing at the amino-terminal end.
abstract: Protein synthesis in mammalian cells is regulated at the level of the guanine nucleotide exchange factor, eIF-2B, which catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. We have isolated and sequenced cDNA clones encoding the delta-subunit of murine eIF-2B. The cDNA sequence encodes a polypeptide of 544 amino acids with molecular mass of 60 kDa. Antibodies against a synthetic polypeptide of 30 amino acids deduced from the cDNA sequence specifically react with the delta-subunit of mammalian eIF-2B. The cDNA-derived amino acid sequence shows significant homology with the yeast translational regulator Gcd2, supporting the hypothesis that Gcd2 may be the yeast homolog of the delta-subunit of mammalian eIF-2B. Primer extension studies and anchor polymerase chain reaction analysis were performed to determine the 5'-end of the transcript for the delta-subunit of eIF-2B. Results of these experiments demonstrate two different mRNAs for the delta-subunit of eIF-2B in murine cells. The isolation and characterization of two different full-length cDNAs also predicts the presence of two alternate forms of the delta-subunit of eIF-2B in murine cells. These differ at their amino-terminal end but have identical nucleotide sequences coding for amino acids 31-544.
authors.affiliation: Department of Molecular Medicine, School of Medicine, University of Auckland, New Zealand.
authors.forename: R A
authors.initials: RA
authors.lastname: Henderson
authors.forename: G W
authors.initials: GW
authors.lastname: Krissansen
authors.forename: R Y
authors.initials: RY
authors.lastname: Yong
authors.forename: E
authors.initials: E
authors.lastname: Leung
authors.forename: J D
authors.initials: JD
authors.lastname: Watson
authors.forename: J N
authors.initials: JN
authors.lastname: Dholakia
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D017124:Conserved Sequence; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D015698:Genomic Library; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D015151:Immunoblotting; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D010954:Plasmacytoma; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis / Q000302:isolation & purification; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D017931:DNA Primers; D018076:DNA, Complementary; D020662:Guanine Nucleotide Exchange Factors; D046911:Macromolecular Substances; D010455:Peptides; D011506:Proteins