Molecular analysis of cDNA clones and the corresponding genomic coding sequences of the Drosophila dunce' gene, the structural gene for cAMP phosphodiesterase

Abstract

We have isolated and sequenced cDNA clones representing portions of the polyadenylylated transcripts of the dunce+ gene. These define an open reading frame of 1086 bases and some of the 5'- and 3'-untranslated regions of the transcripts. The deduced amino acid sequence is strikingly homologous to the amino acid sequence of a Ca^2+/calmodulin-dependent cyclic nucleotide phosphodiesterase isolated from bovine brain and more weakly related to the predicted amino acid sequence of a yeast cAMP phosphodiesterase. These homologies, together with prior genetic and biochemical studies, provide unambiguous evidence that dunce^+ codes for a phosphodiesterase. In addition, the dunce^+ gene product shares a seven-amino acid sequence with a regulatory subunit of cAMP-dependent protein kinase that is predicted to be part of the cAMP binding site. We also identify a weak homology between a region of the dunce+ gene product and the egg-laying hormone precursor of Aplysia californica. The open reading frame is divided in the genome by four introns