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70-S Ribosomes of Escherichia coli Have an Additional Site for Deacylated tRNA Binding.
- Source :
-
European Journal of Biochemistry . 11/1/82, Vol. 128 Issue 1, p47-52. 6p. - Publication Year :
- 1982
-
Abstract
- Escherichia coli 70-S ribosomes contain a third site for tRNA binding, additional to the A and P sites. This conclusion is based on several findings. Direct measurements showed that in the presence of poly(U), when both A and P sites are occupied by Ac[14C]Phe-tRNAPhe, ribosomes are capable of binding additionally deacylated non-cognate [³H]tRNA. If ribosomes in the preparation are active enough, the total binding of labeled ligands amounted to 2.5 mol/mol ribosomes. In the absence of poly(U), when the A site can not bind, the P site and the ‘additional’ site can be filled simultaneously with Ac[14C]Phe-tRNAPhe and deacylated [³H]tRNA, or with [³H]tRNA alone; the total binding exceeds in this case 1.5 mol/mol ribosomes. The binding at the ‘additional’ site is not sensitive to the template. [³H]tRNA bound there is able to exchange rapidly for unlabeled tRNA in solution. Deacylated tRNA is prefered to the aminoacylated one. The binding of AcPhe-tRNAPhe was not observed there at all. The 3′-end adenosine is essential for the affinity. The function of the ‘additional’ site is not known, but its existence has to be considered when tRNA · ribosome complexes are studied. [ABSTRACT FROM AUTHOR]
- Subjects :
- *ESCHERICHIA coli
*RIBOSOMES
*MICROSOMES
*PROTOPLASM
*TRANSFER RNA
*ADENOSINES
Subjects
Details
- Language :
- English
- ISSN :
- 00142956
- Volume :
- 128
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- European Journal of Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 13759630