Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
14
|
| pubmed:dateCreated |
1987-6-19
|
| pubmed:abstractText |
Recent observations have indicated that eukaryotic initiation factor (eIF)-2 and GTP or GDP normally bind to 60 S ribosomal subunits in rabbit reticulocyte lysate and that when eIF-2 alpha is phosphorylated and polypeptide chain initiation is inhibited, eIF-2 X GDP accumulates on 60 S subunits due to impaired dissociation that is normally mediated by the reversing factor (eIF-2B). Current findings now indicate that inhibition due to phosphorylation of eIF-2 alpha is mediated, at least in part, by the inability to dissociate eIF-2 X GDP from the 60 S subunit of complete initiation complexes. At the onset of inhibition, there is an accumulation of Met-tRNA(f) and eIF-2 on the polysomes, despite a marked reduction in Met-tRNA(f) bound to 40 S subunits and Met-peptidyl-tRNA bound to the polysomes. This initial effect is not associated with the formation of "half-mers" (polysomes containing an extra unpaired 40 S subunit), and the 40 S X Met-tRNA(f) complexes, though reduced, still sediment at 43 S. When inhibition is maximal and the polysomes are largely disaggregated, there is an accumulation of 48 S complexes consisting of a 40 S subunit and Met-tRNA(f) bound to globin mRNA as well as small polysomal half-mers, such that residual protein synthesis occurs to about the same degree on "1 1/2"s and "2 1/2"s as on mono-, di-, and triribosomes. Exogenous eIF-2B increases protein synthesis on mono-, di-, and triribosomes and decreases that on half-mers. This is associated with reduced binding of Met-tRNA(f) and eIF-2 to ribosomal particles sedimenting at 80 S and greater and a shift from 48 S to 43 S complexes. These results suggest that eIF-2B must normally promote dissociation of eIF-2 X GDP from the 60 S subunit of complete initiation complexes before they can elongate but cannot when eIF-2 alpha is phosphorylated, resulting in the accumulation of these complexes, some of which dissociate into Met-tRNA(f) X 40 S X mRNA and 60 S X eIF-2 X GDP.
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| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Eukaryotic Initiation Factor-2,
http://linkedlifedata.com/resource/pubmed/chemical/Globins,
http://linkedlifedata.com/resource/pubmed/chemical/Guanine Nucleotides,
http://linkedlifedata.com/resource/pubmed/chemical/Guanosine Diphosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Heme,
http://linkedlifedata.com/resource/pubmed/chemical/Macromolecular Substances,
http://linkedlifedata.com/resource/pubmed/chemical/Peptide Initiation Factors,
http://linkedlifedata.com/resource/pubmed/chemical/Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/RNA, Messenger,
http://linkedlifedata.com/resource/pubmed/chemical/RNA, Transfer, Amino Acyl,
http://linkedlifedata.com/resource/pubmed/chemical/RNA, Transfer, Met,
http://linkedlifedata.com/resource/pubmed/chemical/tRNA, formylmethionine-
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
May
|
| pubmed:issn |
0021-9258
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
15
|
| pubmed:volume |
262
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
6899-907
|
| pubmed:dateRevised |
2007-11-14
|
| pubmed:meshHeading |
pubmed-meshheading:3646234-Animals,
pubmed-meshheading:3646234-Eukaryotic Initiation Factor-2,
pubmed-meshheading:3646234-Globins,
pubmed-meshheading:3646234-Guanine Nucleotides,
pubmed-meshheading:3646234-Guanosine Diphosphate,
pubmed-meshheading:3646234-Heme,
pubmed-meshheading:3646234-Kinetics,
pubmed-meshheading:3646234-Macromolecular Substances,
pubmed-meshheading:3646234-Peptide Initiation Factors,
pubmed-meshheading:3646234-Phosphorylation,
pubmed-meshheading:3646234-Polyribosomes,
pubmed-meshheading:3646234-Protein Binding,
pubmed-meshheading:3646234-Protein Biosynthesis,
pubmed-meshheading:3646234-Proteins,
pubmed-meshheading:3646234-RNA, Messenger,
pubmed-meshheading:3646234-RNA, Transfer, Amino Acyl,
pubmed-meshheading:3646234-RNA, Transfer, Met,
pubmed-meshheading:3646234-Rabbits,
pubmed-meshheading:3646234-Reticulocytes
|
| pubmed:year |
1987
|
| pubmed:articleTitle |
Evidence that phosphorylation of eIF-2(alpha) prevents the eIF-2B-mediated dissociation of eIF-2 X GDP from the 60 S subunit of complete initiation complexes.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
|