The ribosomal A site-bound sense and stop codons are similarly positioned towards the A1823-A1824 dinucleotide of the 18S ribosomal RNA.
Positioning of the mRNA codon towards the 18S ribosomal RNA in the A site of human 80S ribosomes has been studied applying short mRNA analogs containing either the stop codon UAA or the sense codon UCA with a perfluoroaryl azide group at the uridine residue. Bound to the ribosomal A site, a modified codon crosslinks exclusively to the 40S subunits under mild UV irradiation. This result is inconsistent with the hypothesis [Ivanov et al. (2001) RNA 7, 1683-1692] which requires direct contact between the large rRNA and the stop codon of the mRNA as recognition step at translation termination. Both sense and stop codons crosslink to the same A1823/A1824 invariant dinucleotide in helix 44 of 18S rRNA. The data point to the resemblance between the ternary complexes formed at elongation (sense codon.aminoacyl-tRNA.AA dinucleotide of 18S rRNA) and termination (stop codon.eRF1.AA dinucleotide of 18S rRNA) steps of protein synthesis and support the view that eRF1 may be considered as a functional mimic of aminoacyl-tRNA.
Bulygin
Konstantin N
KN
Novosibirsk Institute of Bioorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.
A  Demeshkina
Natalia
N
Frolova
Ludmila Yu
LY
Graifer
Dmitri M
DM
Ven'yaminova
Aliya G
AG
Kisselev
Lev L
LL
Karpova
Galina G
GG
D001386:Azides; D001483:Base Sequence; D001665:Binding Sites; D003062:Codon; D018388:Codon, Terminator; D003432:Cross-Linking Reagents; D015226:Dinucleoside Phosphates; D009843:Oligoribonucleotides / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl; D012360:RNA, Transfer, Phe
D001386:Azides; D003062:Codon; D018388:Codon, Terminator; D003432:Cross-Linking Reagents; D015226:Dinucleoside Phosphates; D009843:Oligoribonucleotides; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012337:RNA, Ribosomal, 18S; D012346:RNA, Transfer, Amino Acyl; D012360:RNA, Transfer, Phe