-transparent.png){kind=logo}
Modeccin inhibits polypeptide-chain elongation catalysed by Artemia salina (brine shrimp) ribosomes by inactivating the 60 S ribosomal subunit. Among the individual steps of elongation, peptide-bond formation, catalysed by 60 S peptidyltransferase, is unaffected by the toxin, whereas the binding of EF 2 (elongation factor 2) to ribosomes is strongly inhibited. Modeccin does not affect the poly(U)-dependent non-enzymic binding of either deacylated tRNAPhe or phenylalanyl-tRNA to ribosomes. The inhibitory effect of modeccin on the EF 1 (elongation factor 1)-dependent binding of phenylalanyl-tRNA is discussed, since it is decreased by tRNAPhe, which stimulates the binding reaction. The analysis of the distribution of ribosome-bound radioactivity during protein synthesis shows that modeccin consistently inhibits the radioactivity bound as long-chain peptides, but depending on the experimental conditions, can leave unchanged or even greatly stimulates the radioactivity bound as phenylalanyl-tRNA and/or short-chain peptides. It is concluded that, during the complete elongation cycle, modeccin does not affect the binding of the first aminoacyl-tRNA to ribosomes, but inhibits some step in the subsequent repetitive activity of either EF 1 or EF 2. The results obtained indicate that the mechanism of action of modeccin is very similar to that of ricin and related plant toxins such as abrin and crotin.
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
January 1969,
Cold Spring Harbor symposia on quantitative biology,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
August 1972,
Nature,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
May 1994,
Molecular biology reports,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
July 1970,
Nature,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
January 1990,
Acta biochimica Polonica,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
April 1994,
The American journal of physiology,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
September 1988,
The Journal of antibiotics,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
April 2011,
Cell biochemistry and function,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
May 1969,
Proceedings of the National Academy of Sciences of the United States of America,
L Montanaro, and
S Sperti, and
M Zamboni, and
M Denaro, and
G Testoni, and
A Gasperi-Campani, and
F Stirpe
November 2002,
European journal of biochemistry,
