[Regulation of biosynthesis of molecular forms of ceruloplasmin in rat ontogenesis]

Ceruloplasmin (CP) expression at the level of formation of its molecular forms in the liver and other rat organs during ontogenesis has been studied. The synthesis of CP commenced on day 15th of embryogenesis and coincided in time with the completion of formation of the fetal liver. This period of rat embryo development was marked by the appearance of two molecular forms of newly formed CP, one of which was secreted in vitro by isolated fetal liver, while the other one was found in the membrane fraction of extrahepatic embryonic tissues. The proportion of CP among the total protein of these fractions increased up to term, correlating with the gain in the embryo weight. The relative content of CP secreted by the livers of newborn animals remained constant up to day 9th of postnatal life and then increased with the age up to approximately 1.5 months. At the same time, the serum concentration of CP remained constant up to day 19th of postnatal life. The increased rate of secreted CP synthesis in the liver during ontogenesis coincided with the appearance of a newly formed non-secreted membrane-bound form of CP in hepatocytes. The ontogenetic dynamics of synthesis of various molecular forms of CP in the liver correlated with the results of immunoblotting of CP polypeptides in Golgi membranes isolated from the livers and the livers and the liver of a 30-day-old rat.