GENOMIC STRUCTURE AND CHROMOSOME LOCATION OF THE MURINE PDE1B PHOSPHODIESTERASE GENE

Cyclic nucleotide phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP and cGMP, thereby participating in regulation of the intracellul ar concentrations of these second messengers. The PDE1 family is defin ed by regulation of activity by calcium and calmodulin. We have cloned and characterized the mouse PDE1B gene, which encodes the 63-kDa calc ium/calmodulin-dependent PDE (CaM-PDE), an isozyme that is expressed i n the CNS in the olfactory tract, dentate gyrus, and striatum and may participate in learning, memory, and regulation of phosphorylation of DARPP-32 in dopaminergic neurons. We screened an I-129/SvJ mouse genom ic library and identified exons 2-13 of the PDE1B gene that span 8.4 k b of genomic DNA. Exons range from 67 to 205 nucleotides and introns f rom 91 to 2250 nucleotides in length. Exon 1 was not present in the 3 kb of genomic DNA 5' to exon 2 in our clones. The mouse PDE1B gene sha res many similar or identical exon boundaries as well as considerable sequence identity with the rat PDE4B and PDE4D genes and the Drosophil a dunce cAMP-specific PDE gene dnc, suggesting that these genes all ar ose from a common ancestor. Using fluorescence in situ hybridization, we localized the PDE1B gene to the distal tip of mouse Chromosome (Chr ) 15.