Mechanism of translocation: relative arrangement of tRNA and mRNA on the ribosome.

AUTOR(ES)

Matzke, A J

RESUMO

AcPhe-tRNAPhe from yeast can be photocross-linked to poly(U) on Escherichia coli ribosomes. The photoreaction occurs at the wybutine base situated next to the 3' side of the anticodon. The kinetics and efficiency of crosslinking of AcPhe-Phe-tRNA are the same at both the acceptor site and the peptidyl site. Therefore, the orientation of wybutine with respect to the mRNA is similar in both the pretranslocational and posttranslocational states. AcPhe-Phe-tRNA crosslinked at the acceptor site can still be translocated to the peptidyl site, demonstrating that tRNA and mRNA are transported together. The experiments support a model of translocation in which the conformation of the anticodon loop of tRNA is similar in both the peptidyl site and the acceptor site.

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