Evidence that eukaryotic initiation factor (eIF) 2 is a cap-binding protein that stimulates cap recognition by eIF-4B and eIF-4F.
We studied the mRNA-binding properties of eukaryotic initiation factor (eIF) 2. This Met-tRNA-binding factor interacts with the cap structure of reoviral mRNA in an ATP-independent manner. Both the beta- and gamma-subunit of eIF-2 are involved in the UV-induced cross-linking of eIF-2 to the cap. The interaction of eIF-2 with a messenger is sensitive to the cap analogue 7-methyl-guanosine 5'-triphosphate as measured by cross-linking and by mRNA retention on nitrocellulose filters. The cap-binding property of eIF-2 does not conflict with the current mRNA-binding model of initiation factors eIF-4A, -4B, and -4F: cross-linking of eIF-4E and of eIF-4B is stimulated by eIF-2. The eIF-2-mediated increase of eIF-4E interaction results in a decrease of the cross-linking of the beta- and gamma-subunits of eIF-2. The presence of GTP in the cross-linking assay interferes with the interaction of eIF-2 with the cap structure but does not inhibit the eIF-2 stimulated eIF-4E and -4B cross-linking. These observations indicate a role for eIF-2 in the mRNA recognition.
van Heugten
H A
HA
Department of Molecular Cell Biology, University of Utrecht, The Netherlands.
Kasperaitis
M A
MA
Thomas
A A
AA
Voorma
H O
HO
D000818:Animals; D002460:Cell Line; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism* / Q000528:radiation effects; D039562:Eukaryotic Initiation Factor-4F; D039642:Eukaryotic Initiation Factors; D007700:Kinetics; D012089:Mammalian orthoreovirus 3 / Q000235:genetics; D010448:Peptide Initiation Factors / Q000378:metabolism*; D011485:Protein Binding; D012315:RNA Caps / Q000378:metabolism* / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism*; D014466:Ultraviolet Rays
D015852:Eukaryotic Initiation Factor-2; D039562:Eukaryotic Initiation Factor-4F; D039642:Eukaryotic Initiation Factors; D010448:Peptide Initiation Factors; D012315:RNA Caps; D012333:RNA, Messenger; C031799:eIF-4B