The Biosynthesis of Protamine in Trout Testis

Abstract

Abstract Protamine isolated from rainbow trout testis can be separated into three main components, Ci, Cii, and Ciii, by chromatography on microgranular carboxymethyl cellulose columns. After further purification by rechromatography on the same column, each component was analyzed for amino acid content. These analyses indicated that the components were distinct but closely related. However, each component still appeared heterogeneous since the number of residues of different amino acids assumed nonintegral values. The relative amounts of the protamine components present in spermatid nuclei were different at different stages of spermatogenesis. It appeared that the relative amount of Ci decreased while Ciii increased during testis maturation probably as the result of differing rates of synthesis of each component. The probable function of protamine is in the packaging of DNA into the sperm head. The independent synthesis of protamine components suggests that, in spite of their similarities, they may have different specific functions.