Developmental regulation of secretory protein synthesis in rat seminal vesicle

This paper reports a developmental study of one of the major secretory proteins (SVS IV) of the rat seminal vesicle. Measured by radioimmunoassay, SVS IV is detectable even in very young rats (5 days old) but does not begin to accumulate in massive amounts until animals reach about 35 days of age. We have compared SVS IV synthesis by minced tissue from rats undergoing sexual maturation (25-60 days of age) with levels of translatable SVS IV mRNA present. Between 25 and 60 days of age, the proportion of newly synthesized protein devoted to SVS IV by tissue minces increased from 0.8% to 20%. In contrast, the proportion of total RNA devoted to translatable SVS IV mRNA was already high in the immature glands and increased less than 4-fold during development. These results seem to indicate that factors other than the presence of potentially translatable message regulate the rate of net synthesis of SVS IV during seminal vesicle maturation.