A 45-kDa cAMP-dependent phosphoprotein which is related to the product of Mst57Dc in Drosophila melanogaster

In Drosophila, the catalytic subunit of cAMP-dependent protein kinase (PKA) is preferentially expressed in the brain and the male reproductive organs. Although the cAMP response element binding protein (CREB) is a major targe t of PKA in the brain, the target of PKA in the male reproductive organs ha s been unknown. In the present study, three cAMP-dependent phosphoproteins (referred to as pp45, pp20, and pp10) were detected in the lumen fluid of m ale accessory glands. They were tissue-specific secretory proteins that acc umulated only after eclosion, and were transferred to females during mating as other secretory proteins of the accessory glands. Among them, the 45-kD a phosphoprotein was partially purified and characterized. The purified pro tein was phosphorylated in vitro by the catalytic subunit of PKA. The parti al amino acid sequence of this 45-kDa phosphoprotein was identical to the p redicted amino acid sequence of the Mst57Dc cDNA, which is a male accessory gland transcript. (C) 1999 Published by Elsevier Science Ltd. All rights r eserved.