Cloning and expression of cDNAs for the beta subunit of eukaryotic initiation factor-2B, the guanine nucleotide exchange factor for eukaryotic initiation factor-2.
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 epsilon, delta, gamma, beta and alpha. To clone cDNAs for the beta 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 lambda gt11 to obtain full-length cDNAs for eIF-2B beta. 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-2B beta 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-2B beta. Northern-blot analysis revealed a single major mRNA species for eIF-2B beta in each of the four rabbit tissues tested.
Craddock
B L
BL
Department of Biochemistry, School of Medical Sciences, University of Bristol U.K.
Price
N T
NT
Proud
C G
CG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D015852:Eukaryotic Initiation Factor-2; D020662:Guanine Nucleotide Exchange Factors; D011506:Proteins; D012333:RNA, Messenger