scholarly journals Inhibition of protein synthesis by ricin: experiments with rat liver mitochondria and nuclei and with ribosomes from Escherichia coli

1974 ◽  
Vol 142 (3) ◽  
pp. 695-697 ◽  
Author(s):  
Margherita Greco ◽  
Lucio Montanaro ◽  
Francesco Novello ◽  
Cecilia Saccone ◽  
Simonetta Sperti ◽  
...  

1. Ricin, a toxic protein from the seeds of Ricinus communis which inhibits poly(U)-directed polyphenylalanine synthesis by rat liver ribosomes (Montanaro et al., 1973), does not affect protein synthesis by isolated rat liver mitochondria. 2. The toxin is ineffective also on poly(U)-directed polyphenylalanine synthesis in reconstituted systems with ribosomes isolated from rat liver mitochondria or from Escherichia coli. 3. Ricin inhibits protein synthesis by isolated rat liver nuclei, but at concentrations much higher than those affecting rat liver ribosomes.

1968 ◽  
Vol 22 ◽  
pp. 3072-3080 ◽  
Author(s):  
O. Hänninen ◽  
K. Alanen-Irjala ◽  
Gunilla Carlsson ◽  
Olav Smidsrød

1969 ◽  
Vol 111 (5) ◽  
pp. 653-663 ◽  
Author(s):  
D. Haldar ◽  
K. B. Freeman

1. Incorporation of [14C]leucine into protein by isolated rat liver mitochondria was examined by using incubation media similar to those used by Sandell, Löw & Decken (1967) (medium A) and Roodyn, Reis & Work (1961) (medium B). The incorporation process was found to be almost completely inhibited in medium A. 2. By decreasing the amount of sucrose and omitting tris–hydrochloric acid from medium A, incorporation proceeded at a rate higher than that found in medium B. It was found that the inhibitory action of medium A was due to its high osmolarity. 3. Oxidative phosphorylation and RNA synthesis by the isolated mitochondria proceeded at the same rate in media essentially the same as media A and B. 4. There was a partial inhibitory action of medium A on leucine uptake by the mitochondria and also on the formation of leucyl-transfer-RNA. The major block of inhibition by the hyperosmolarity of medium A seemed to be located at a later step of protein synthesis involving mitochondrial ribosomes. 5. Protein synthesis by Escherichia coli B was only slightly inhibited, if at all, in hyperosmotic media in which protein synthesis by isolated mitochondria was completely stopped.


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