TY - JOUR
T1 - Recognition of Messenger RNA in Eukaryotic Protein Synthesis
T2 - Equilibrium Studies of the Interaction between Messenger RNA and the Initiation Factor that Binds Methionyl‐tRNAf
AU - KAEMPFER, Raymond
AU - HOLLENDER, Rivka
AU - SOREQ, Hermona
AU - NUDEL, Uri
PY - 1979/3
Y1 - 1979/3
N2 - Equilibrium studies of the interaction between messenger RNA and the rabbit reticulocyte initiation factor that binds methionyl‐tRNAf, eIF‐2, were performed, using filtration through nitrocellulose membranes to measure complex formation. The formation of complexes between the initiation factor and messenger RNA is shown to be consistent with a simple, bimolecular equilibrium. Binding of native, translatable 125I‐labeled globin messenger RNA to the factor is tight, with an apparent dissociation constant of approximately 5 × 10 −10 M at physiological salt concentration. This binding does not involve the poly(A) sequence at the 3′ end of globin messenger RNA, nor the 90‐nucleotide sequence adjacent to it, for poly(A)‐free derivatives of globin messenger RNA prepared by controlled, processive phosphorolysis bind the initiation factor with an affinity essentially equal to that of native globin messenger RNA. In contrast to other cases of protein‐nucleic‐acid interaction, binding of initiation factor eIF‐2 to messenger RNA is as tight at 0.15 M KCI as it is at 0.01 M KCI and is consistent with a preference for the RNA conformation existing at physiological salt concentration. 32P‐labeled bacteriophage R17 RNA, a messenger RNA that can be translated, although at relatively low efficiency, in a mammalian cell‐free system, also forms an equimolar complex with eIF‐2, but binds 10 to 15‐fold less tightly than globin messenger RNA. These results show that the eukaryotic initiation factor that binds methionyl‐tRNAf recognizes a sequence in globin messenger RNA that does not include the poly(A) moiety or most of the untranslated sequence at the 3′ end of the molecule. The data suggest a relationship between the affinity of a given messenger RNA species for initiation factor eIF‐2 and its efficiency as a template in protein synthesis.
AB - Equilibrium studies of the interaction between messenger RNA and the rabbit reticulocyte initiation factor that binds methionyl‐tRNAf, eIF‐2, were performed, using filtration through nitrocellulose membranes to measure complex formation. The formation of complexes between the initiation factor and messenger RNA is shown to be consistent with a simple, bimolecular equilibrium. Binding of native, translatable 125I‐labeled globin messenger RNA to the factor is tight, with an apparent dissociation constant of approximately 5 × 10 −10 M at physiological salt concentration. This binding does not involve the poly(A) sequence at the 3′ end of globin messenger RNA, nor the 90‐nucleotide sequence adjacent to it, for poly(A)‐free derivatives of globin messenger RNA prepared by controlled, processive phosphorolysis bind the initiation factor with an affinity essentially equal to that of native globin messenger RNA. In contrast to other cases of protein‐nucleic‐acid interaction, binding of initiation factor eIF‐2 to messenger RNA is as tight at 0.15 M KCI as it is at 0.01 M KCI and is consistent with a preference for the RNA conformation existing at physiological salt concentration. 32P‐labeled bacteriophage R17 RNA, a messenger RNA that can be translated, although at relatively low efficiency, in a mammalian cell‐free system, also forms an equimolar complex with eIF‐2, but binds 10 to 15‐fold less tightly than globin messenger RNA. These results show that the eukaryotic initiation factor that binds methionyl‐tRNAf recognizes a sequence in globin messenger RNA that does not include the poly(A) moiety or most of the untranslated sequence at the 3′ end of the molecule. The data suggest a relationship between the affinity of a given messenger RNA species for initiation factor eIF‐2 and its efficiency as a template in protein synthesis.
UR - http://www.scopus.com/inward/record.url?scp=0018449902&partnerID=8YFLogxK
U2 - 10.1111/j.1432-1033.1979.tb12929.x
DO - 10.1111/j.1432-1033.1979.tb12929.x
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C2 - 428400
AN - SCOPUS:0018449902
SN - 0014-2956
VL - 94
SP - 591
EP - 600
JO - European Journal of Biochemistry
JF - European Journal of Biochemistry
IS - 2
ER -