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Phosphorylation of eukaryotic initiation factor EIF-4E

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:6029458
; ; ; ;
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-
Conference Information:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ENZYMES
FRACTIONATION
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
MESSENGER-RNA
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RABBITS
RADIOISOTOPES
RNA
SEPARATION PROCESSES
SERINE
SUBSTRATES
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES