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

Journal Article · Tue Nov 05 04:00:00 EST 1985 · J. Biol. Chem.; (United States)

OSTI ID:6086294

Sarkar, G; Edery, I; Sonenberg, N

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), Journal Name: J. Biol. Chem.; (United States) Vol. 25; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
560111 -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AFFINITY
ALKALINE EARTH METALS
ANIMALS
ATP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
CROSS-LINKING
DAYS LIVING RADIOISOTOPES
ELECTROMAGNETIC RADIATION
ELEMENTS
IN VITRO
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LIGHT NUCLEI
MAGNESIUM
MAMMALS
MESSENGER-RNA
METALS
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOTOCHEMISTRY
POLYMERIZATION
POLYPEPTIDES
PROTEINS
RABBITS
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RNA
SYNERGISM
TRACER TECHNIQUES
ULTRAVIOLET RADIATION
VERTEBRATES