Duck erythroblasts

After the discovery of this multicatalytic proteinase complex, which has a sedimentation coefficient of 20 S, it was realised that it was very similar to another particle that had been isolated independently. The latter, known as a prosome, is associated with mRNA that is repressed from translation. Generally a cell has two pools of mRNA, one that is being actively translated and the other that is inhibited from translation. Prosome-like particles have been detected in duck erythroblasts where they inhibit translation of the portion of the mRNA that is bound to the erythroblasts (Akhayat et al, 1967 Nothwang et al, 1992). The multicatalytic proteinase (20S) associates with two factors (CFl and CF2) to form a 26S complex referred to as a proteasome (Fig. 5.4). The proteasome (26S) and the multicatalytic proteinase complex (20S) are thought to participate in ubiquitin-dependent and ubiquitin-independent proteolysis, respectively. 

Coux, O., Camoin, L., Nothwang, H.-G. et al (1992a). The protein of Mr 21000 constituting the prosome-like particle of duck erythroblasts is homologous to apoferritin. Eur. ]. Biochem., 207, 823-32. 

Nothwang, H.G., Coux, O., Keith, G., Silva-Pereira, 1. Scherer, K. (1992). The major RNA in. prosomes of Hela cells and duck erythroblasts is tRNA. Nucl Acids Res., 20,1959-65. 

Scherrer, K., L. Marcaud, F. Zajdela, I. M. London, and F. Gros. 1966. Patterns of RNA metabolism in a differentiated cell A rapidly labeled, unstable 60S RNA with messenger properties in duck erythroblasts. Proc. Nat. Acad. Sci. U.S.A., 56 1571-1578. 

Vincent A, Goldenberg N, Standart N, Civelli 0, Imaizumi-Scherrer T, Maundrell K, Scherrer K (1981) Potential role of mRNP proteins in cytoplasmic control of gene expression in duck erythroblasts. Mol Biol Rep 7 71-81... 

Our own studies on mRNA and hemoglobin synthesis have been carried out primarily in duck erythroblasts. Earher studies in duck erythrocytes had indicated the usefulness of this system for the study of heme and globin synthesis (Shemin et al., 1948 Kassenaar et at, 1957). By inducing profound hemolytic anemia in ducks with acetyl-phenylhydrazine, one can obtain in the peripheral blood very immature erythroblasts with a strikingly increased capacity for the synthesis of RNA and protein. Studies begun in collaboration with Gros and subsequently extended by Scherrer et al. (1966a,b) will be summarized briefly. 

On incubation of duck erythroblasts with tritiated inidine for periods of 30 to 270 minutes, one observes rapid labeling of heavy RNA species... 

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