title: NPP-type ectophosphodiesterases: unity in diversity.
abstract: Nucleotide pyrophosphatase/phosphodiesterase (NPP)-type ectophosphodiesterases are found at the cell surface as type-I or type-II transmembrane proteins, but are also found extracellularly as secreted or shedded enzymes. They hydrolyze pyrophosphate or phosphodiester bonds in a variety of extracellular compounds including nucleotides, (lyso)phospholipids and choline phosphate esters. Despite their structurally related catalytic domain, each enzyme has well-defined substrate specificity. Catalysis by NPPs affects processes as diverse as cell proliferation and motility, angiogenesis, bone mineralization and digestion. In addition, there is emerging evidence for non-catalytic functions of NPPs in cell signaling. NPP-type ectophosphodiesterases are also implicated in the pathophysiology of cancer, insulin resistance and calcification diseases, and they hold great promise as easily accessible therapeutic targets.
authors.affiliation: Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Stefan
authors.forename: Silvia
authors.initials: S
authors.lastname: Jansen
authors.forename: Mathieu
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000818:Animals; D002465:Cell Movement; D049109:Cell Proliferation; D006801:Humans; D018919:Neovascularization, Physiologic; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011755:Pyrophosphatases / Q000378:metabolism*; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D010727:Phosphoric Diester Hydrolases; D011755:Pyrophosphatases; C405782:nucleotide pyrophosphatase - phosphodiesterase I