Premium
Correlation between the distribution of the reversing factor and eukaryotic initiation factor 2 in heme‐deficient or double‐stranded RNA‐inhibited reticulocyte lysates
Author(s) -
Matts Robert L.,
Thomas N.Shaun B.,
Hurst Robin,
London Irving M.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80310-7
Subject(s) - reticulocyte , initiation factor , ribosome , gtp' , eukaryotic initiation factor , protein subunit , heme , chemistry , eukaryotic small ribosomal subunit , rna , biology , microbiology and biotechnology , biochemistry , enzyme , gene
The recycling of eukaryotic initiation factor eIF‐2 requires the exchange of GDP for GTP, in a reaction catalyzed by the reversing factor (RF). Recent studies have suggested that a 60 S ribosomal subunit‐bound eIF‐2 · GDP complex is an intermediate in protein chain initiation. We have monitored the distribution of RF in heme‐deficient and dsRNA‐inhibited lysates by immunoblot analysis of sucrose gradient fractions and have compared the distribution with that of eIF‐2(α‐ 32 P). RF and eIF‐2(αP) were both found to be tightly associated with 60 S and 80 S ribosomes, as their distribution did not change in gradients containing up to 0.1 M K + . The association of eIF‐2(α‐ 32 P) and RF with 60 S and 80 S ribosomes was enhanced in the presence of F − , indicating the presence of an endogenous ribosome‐associated phosphatase activity which is capable of dephosphorylating eIF‐2(αP) in the absence of F − . These observations are consistent with the hypothesis that under physiologic conditions, RF interacts with the 60 S‐bound eIF‐2 · GDP complex to promote the dissociation of GDP from eIF‐2 and the release of eIF‐2 from the 60 S subunit as a complex with RF.