Effects of Ricin on the Ribosomal Sites Involved in the Interaction of the Elongation Factors
- 28 June 1975
- journal article
- Published by Wiley in European Journal of Biochemistry
- Vol. 54 (2) , 499-503
- https://doi.org/10.1111/j.1432-1033.1975.tb04162.x
Abstract
The effects of ricin on the different steps of the elongation cycle of protein synthesis in a rabbit reticulocyte cell-free system are studied in this paper. The toxin most probably acts by catalytically inactivating the ribosomes, since a single molecule of the toxin can inactivate 300 ribosomes for poly(U)-directed phenylalanine incorporation. The effect of the toxin on the ribosome is irreversible. Ricin specifically inhibits elongation-factor-1-dependent aminoacyl-tRNA binding to ribosomes but has no effect on the non-enzymic binding of aminoacyl-tRNA. Ricin also inhibits formation of the complex elongation-factor-2 - ribosome - nucleotide with GTP, GDP or GMP-P(CH2)P. However, the toxin has no effect on translocation. These apparently conflicting results are discussed in this study.Keywords
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