ectonucleotide pyrophosphatase/phosphodiesterase family member 6; E-NPP 6; NPP-6; choline-specific glycerophosphodiester phosphodiesterase; glycerophosphocholine cholinephosphodiesterase (ENPP6)

Function: 1) choline-specific glycerophosphodiester phosphodiesterase 2) lysophospholipase C activity a) hydrolyzes lysophosphatidylcholine to form monoacylglycerol & phosphorylcholine b) hydrolyzes the classical substrate for phospholipase C, p-nitrophenyl phosphorylcholine b) does not hydrolyze lysophosphatidic acid 3) preference for lysophosphatidylcholine with short (12:0 & 14:0) or polyunsaturated (18:2 & 20:4) fatty acids 4) hydrolyzes glycerophosphorylcholine & sphingosylphosphoryl- choline 5) does not hydrolyze the classical nucleotide phosphodiesterase substrate, p-nitrophenyl thymidine 5'-monophosphate 6) does not hydrolyze diacyl phospholipids such as phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol or phosphatidic acid Cofactor: divalent cations Inhibition: - inhibited by EDTA & EGTA in vitro Kinetic parameters: - KM=344 uM for GPC - KM=296 uM for 12:0-LPC - KM=440 uM for 14:0-LPC - KM=165 uM for 16:0-LPC - KM=434 uM for 18:2-LPC - KM=563 uM for 20:4-LPC - Vmax=484 nmol/min/mg enzyme with GPC as substrate - Vmax=463 nmol/min/mg enzyme with 12:0-LPC as substrate - Vmax=367 nmol/min/mg enzyme with 14:0-LPC as substrate - Vmax=89 nmol/min/mg enzyme with 16:0-LPC as substrate - Vmax=285 nmol/min/mg enzyme with 18:2-LPC as substrate - Vmax=470 nmol/min/mg enzyme with 20:4-LPC as substrate - pH dependence: optimum pH is 8.5-7.5 Structure: - belongs to the nucleotide pyrophosphatase/phosphodiesterase family Compartment: - cell membrane, - a minor secreted form Expression: predominantly expressed in kidney & brain

General

glycoprotein membrane protein phosphodiesterase

Properties

SIZE: entity length = 440 aa MW = 50 kD COMPARTMENT: cellular membrane MOTIF: signal sequence {1-22} serine residue {S71} N-glycosylation site {N118} N-glycosylation site {N341} transmembrane domain {420-438}

Database Correlations

UniProt Q6UWR7 Pfam PF01663 Entrez Gene 133121 Kegg hsa:133121 ENZYME 3.1.4.38

References

UniProt :accession Q6UWR7