Cloning and expression of cDNAs for the β subunit of eukaryotic initiation factor-2B, the guanine nucleotide exchange factor for eukaryotic initiation factor-2

B. L. Craddock, N. T. Price, C. G. Proud

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A key control point in the initiation of protein synthesis in mammalian cells is the recycling of eukaryotic initiation factor (eIF)-2 by the guanine nucleotide exchange factor eIF-2B. In mammalian cells, eIF-2B is a complex of five different subunits termed ε, δ, γ, β and α. To clone cDNAs for the β subunit of rabbit eIF-2B, amino acid sequence data was first obtained and used to design redundant oligonucleotide primers for use in PCR. PCR products were used to screen a rabbit liver cDNA library in λgt11 to obtain full-length cDNAs for eIF-2Bβ. The cDNAs were sequenced completely on both strands and revealed an open reading frame encoding a predicted 351-amino acid polypeptide of 39.0 kDa. The molecular mass and pI (5.99) of the predicted protein agree well with the properties of eIF-2Bβ purified from rabbit reticulocytes. In vitro transcription/translation of the cDNAs gave rise to a product that migrated at a position indistinguishable from that of this subunit of the purified protein. The amino acid sequence shows a high degree of similarity to that of GCD7, a Saccharomyces cerevisiae protein thought to be equivalent to mammalian eIF-2Bβ. Northern-blot analysis revealed a single major mRNA species for eIF-2Bβ in each of the four rabbit tissues tested.

Original languageEnglish
Pages (from-to)1009-1014
Number of pages6
JournalBiochemical Journal
Issue number3
Publication statusPublished or Issued - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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