Ectophosphodiesterase/nucleotide phosphohydrolase (Enpp) nucleotidases: cloning, conservation and developmental restriction.

Ectonucleotidase proteins occupy a central role in purine signalling regulation by sequentially hydrolysing ATP to ADP and to adenosine. The ENPP ( or PDNP) gene family, which encodes ectophosphodiesterase/nucleotide phosphohydrolases, is a subfamily of these enzymes, which consists of 7 members in mammals. These proteins catalyse the generation of bioactive lipids, placing the ENPP enzymes as key regulators of major physiological signalling pathways and also important players in several pathological conditions. Here we report the cloning of all the members, except enpp5, of the enpp family in Xenopus laevis and tropicalis. Phylogenetic analyses demonstrate the high level of conservation of these proteins between amphibian and other vertebrate species. During development and in the adult frog, each gene displays a distinct specific expression pattern, suggesting potentially different functions for these proteins during amphibian embryogenesis. This is the first complete developmental analysis of gene expression of this gene family in vertebrates.