Further biochemical characterization of rabbit reticulocyte eIF-4B.
In this report, it is shown that eIF-4B exhibits ATP hydrolysis activity in a ribosome-dependent fashion. This activity is significantly enhanced by the addition of eIF-4A and eIF-4F, although neither of these factors, alone or together, display a significant ribosome-dependent ATPase activity. Sepharose-6B gel filtration experiments with combinations of nonlabeled and 14C reductively methylated initiation factors (eIF-4A, eIF-4B, eIF-4F, and eIF-3) provide evidence that both eIF-4B and eIF-4F, but not eIF-4A, interact with ribosomes in the presence of specific factors and ATP. It is not known with which ribosomal subunit(s) these factors interact. In ultraviolet radiation-induced crosslinking studies, an eIF-4A and/or eIF-4F and ATP-dependent crosslinking of eIF-4B to radiolabeled oligo(A)12-18 was observed. Past studies with oxidized-cap mRNA achieved cross-linking of all three of these factors, driven by the specific interaction of eIF-4F p24 with the m7GTP cap structure; this is the first reported instance of only eIF-4B cross-linking to RNA.
Hughes
D L
DL
Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
Dever
T E
TE
Merrick
W C
WC
D000227:Adenine Nucleotides / Q000378:metabolism / Q000528:radiation effects; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D039601:Eukaryotic Initiation Factor-4A; D039562:Eukaryotic Initiation Factor-4F; D039642:Eukaryotic Initiation Factors; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism*; D009843:Oligoribonucleotides / Q000378:metabolism / Q000528:radiation effects; D010448:Peptide Initiation Factors / Q000378:metabolism* / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000737:chemistry*; D012270:Ribosomes / Q000378:metabolism*; D014466:Ultraviolet Rays
D000227:Adenine Nucleotides; D039562:Eukaryotic Initiation Factor-4F; D039642:Eukaryotic Initiation Factors; D009711:Nucleotides; D009843:Oligoribonucleotides; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; C031799:eIF-4B; C023505:2',5'-oligoadenylate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D039601:Eukaryotic Initiation Factor-4A; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases