Photoaffinity labeling of the cap-binding protein complex with ATP/dATP. Differential labeling of free eukaryotic initiation factor 4A and the eukaryotic initiation factor 4A component of the cap-binding protein complex with (alpha-TSP)ATP/dATP
It has been suggested that the cap-binding protein complex is involved in ATP-mediated melting of 5'-mRNA secondary structure to facilitate ribosome binding during initiation of translation in eukaryotic cells. Consequently, we have studied the interaction of dATP/ATP with the eukaryotic cap-binding protein complex by UV photoaffinity labeling. UV irradiation of the cap-binding protein complex in the presence of (alpha-TSP)dATP/ATP resulted in the cross-linking of this compound to the 50-kDa polypeptide of the complex. This polypeptide is almost identical to the previously characterized eukaryotic initiation factor (eIF) 4A. We examined the ability of dATP/ATP to cross-link to eIF-4A and found that it cross-links less efficiently (approximately 60-fold on a molar basis) compared to the cross-linking obtained for the eIF-4A component of the cap-binding protein complex. Irradiation of purified eIF-4A together with the cap-binding protein complex in the presence of (alpha-TSP)dATP resulted in greater than additive labeling of the eIF-4A component of the cap-binding protein complex and purified eIF-4A, suggesting a synergistic interaction between purified eIF-4A, the cap-binding protein complex, and dATP/ATP. We also report that photoaffinity labeling of eIF-4A and the eIF-4A component in the cap-binding protein complex is stimulated by eIF-4B, but not by other initiation factors or mRNA.
- Research Organization:
- McGill Univ., Montreal, Quebec, Canada
- OSTI ID:
- 6086294
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 25
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
PROTEINS
BIOLOGICAL RADIATION EFFECTS
LABELLING
AFFINITY
ATP
CROSS-LINKING
IN VITRO
MAGNESIUM
MESSENGER-RNA
PHOSPHORUS 32
PHOTOCHEMISTRY
POLYPEPTIDES
RABBITS
SYNERGISM
TRACER TECHNIQUES
ULTRAVIOLET RADIATION
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
ELECTROMAGNETIC RADIATION
ELEMENTS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
METALS
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDES
PHOSPHORUS ISOTOPES
POLYMERIZATION
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RNA
VERTEBRATES
550201* - Biochemistry- Tracer Techniques
560111 - Radiation Effects on Biochemicals- In Vitro- (-1987)