Phosphorylation of eukaryotic initiation factor EIF-4E
Eukaryotic protein synthesis initiation factor eIF-4E is a 25-kDa protein which binds to the cap structure of mRNA and is involved in the entry of mRNA into the initiation of protein synthesis. EIF-4E is isolated as a mixture of phosphorylated and nonphosphorylated forms. The site of phosphorylation was determined to be serine-53 of the eIF-4E sequence. The amino acid sequence surrounding the phosphorylated serine is 40-QNRWALWFFKNDKSKTWQANLRL-62. Tryptic digestion of eIF-4E, labeled with /sup 32/P in intact rabbit reticulocytes, yielded one labeled peptide whose amino acid composition was consistent with the structure SK. After treatment of the protein with citraconic anhydride to block lysyl residues, tryptic digestion yielded a labeled peptide whose composition was consistent with the structure WALWFFKNDKSKTWQANLR. A protein kinase was purified from rabbit reticulocyte lysate which specifically phosphorylated eIF-4E and not other initiation factors. Peptide analysis of the in vitro-phosphorylated protein revealed that a single site was phosphorylated and that it was the same as the in vivo-phosphorylated site. Comparison of eIF-4E and eIF-4F as substrates for the kinase revealed that the K/sub s/ was 15-fold lower for eIF-4F, indicating that the latter is the preferred substrate.
- Research Organization:
- Univ. of Kentucky, Lexington
- OSTI ID:
- 6029458
- Report Number(s):
- CONF-870644-; TRN: 87-037143
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOTRANSFERASES
FRACTIONATION
PROTEINS
AMINO ACID SEQUENCE
PHOSPHORYLATION
MESSENGER-RNA
PEPTIDES
PHOSPHORUS 32
RABBITS
SERINE
SUBSTRATES
TRACER TECHNIQUES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ENZYMES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RADIOISOTOPES
RNA
SEPARATION PROCESSES
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques