ABSTRACT
The cloning of cyclic nucleotide phosphodiesterase 8A (PDE8A) inaugurated the era of bioinformatics-guided PDE discovery that in the span of 2 years led to the fast paced identification of the second member of the family, PDE8B, as well as PDE9A, PDE10A, and PDE11A. PDE8A was initially identified by searching human and mouse expressed sequence tag databases for sequences with homology to the catalytic domain of other PDEs. The biological significance of alternative transcripts for PDE8A and PDE8B is still unclear. The N-terminal portion of PDE8 contains a putative REC and a PAS domain. Northern analysis for PDE8A expression in human, mouse, and rat tissues showed a high expression in testis. The biological functions of PDE8s are still unknown and can only be speculated based on the relevance of 3',5'-cyclic adenosine monophosphate -regulated processes in the particular cell types in which PDE8s are found.
