title: An interaction of wheat germ initiation factor 4B with oligoribonucleotides.
abstract: The binding of oligoribonucleotides to wheat germ protein synthesis initiation factor eIF-4B was measured by direct fluorescence techniques. An analysis of the equilibrium association constants (Keq) indicates that eIF-4B binding is not affected by the m7GTP cap structure or the AUG. eIF-4B is insensitive to hairpin structures within the oligoribonucleotide. The binding site size is approximately 18 bases. The binding of oligoribonucleotide to eIF-4B as a function of pH, temperature, and ionic strength is also described. The pH-dependent binding showed an increase in binding with increasing pH in contrast to the sharp pH optimum observed for cap binding protein eIF-4E (Carberry, S. E., Darzynkiewicz, E., and Goss, D.J. (1991) Biochemistry 30, 1624-1627). Assuming all tryptophan residues contribute to the observed fluorescence, iodide quenching showed that 8(+/- 1) out 9 of eIF-4B's tryptophan residues are on the surface of the eIF-4B protein. A specific anion effect of Cl- on eIF-4B binding to oligoribonucleotide was found when comparing the ionic strength effect of KC2H3O2 and KCl.
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York, New York 10021-5024.
authors.forename: M
authors.initials: M
authors.lastname: Sha
authors.forename: M L
authors.initials: ML
authors.lastname: Balasta
authors.forename: D J
authors.initials: DJ
authors.lastname: Goss
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D039601:Eukaryotic Initiation Factor-4A; D039642:Eukaryotic Initiation Factors; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000378:metabolism*; D012639:Seeds; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014908:Triticum / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
chemical_list: D039642:Eukaryotic Initiation Factors; D009843:Oligoribonucleotides; D010448:Peptide Initiation Factors; C031799:eIF-4B; D014364:Tryptophan; D000255:Adenosine Triphosphate; D039601:Eukaryotic Initiation Factor-4A