Translation of protamine mRNA in a rabbit reticulocyte cell-free system

Abstract

Protamine mRNA isolated from the microsomal and postribosomal supernatant fractions of trout testis in poly A(+) (polyadenylated RNA) and poly A(−) (RNA devoid of poly A(+)) forms (Gedamu, L. &Dixon, G.H. (1976)7. Biol. Chem. 251, 1446–1454 and 1455–1463) was translated in the heterologous rabbit reticulocyte cell-free system; the products were shown to be identical in mobility with authentic protamine by polyacrylamide and starch gel electrophoresis. Chromatography, on carboxymethyl cellulose (Whatman CM-52), of the labelled polypeptide products synthesized in this cell-free system in the presence of poly A(+) and poly A(−) mRNA fractions also showed that [14C]arginine was incorporated into all three protamine components resolved in this system, but there was an unequal and variable incorporation of label into the three components with different preparations of mRNA. These results were interpreted as showing that the population of subcomponents of the protamine mRNA coding for the three different protamine polypeptides varied in batches of trout testis at differing stages of development. In addition, the proportion of mRNA components varied between the poly A(+) and poly A(−) editions of the mRNA, and it appeared that the poly A(−) mRNA fraction might represent the product of deadenylation of an earlier population of poly A(+) mRNA.