Choline-specific glycerophosphodiesterase that hydrolyzes glycerophosphocholine (GPC) and lysophosphatidylcholine (LPC) and contributes to supplying choline to the cells (PubMed:15788404, PubMed:26888014). Has a preference for LPC with short (12:0 and 14:0) or polyunsaturated (18:2 and 20:4) fatty acids (PubMed:15788404). In vitro, hydrolyzes only choline-containing lysophospholipids, such as sphingosylphosphorylcholine (SPC), platelet-activating factor (PAF) and lysoPAF, but not other lysophospholipids (PubMed:15788404). H2O + sn-glycerol 3-phosphocholine = glycerol + H(+) + phosphocholine a 1-acyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycerol + H(+) + phosphocholine 1-O-alkyl-sn-glycero-3-phosphocholine + H2O = 1-O-alkyl-sn-glycerol + H(+) + phosphocholine 1-dodecanoyl-sn-glycero-3-phosphocholine + H2O = 1-dodecanoyl-sn-glycerol + H(+) + phosphocholine 1-hexadecanoyl-sn-glycero-3-phosphocholine + H2O = 1-hexadecanoyl-sn-glycerol + H(+) + phosphocholine 1-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + H2O = 1-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycerol + H(+) + phosphocholine 1-tetradecanoyl-sn-glycero-3-phosphocholine + H2O = 1-tetradecanoyl-sn-glycerol + H(+) + phosphocholine H2O + sphing-4-enine-phosphocholine = H(+) + phosphocholine + sphing-4-enine 1-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine + H2O = 1-(9Z-octadecenoyl)-sn-glycerol + H(+) + phosphocholine 1-(9Z,12Z)-octadecadienoyl-sn-glycero-3-phosphocholine + H2O = 1-(9Z,12Z-octadecadienoyl)-sn-glycerol + H(+) + phosphocholine glycero-2-phosphocholine + H2O = glycerol + H(+) + phosphocholine Binds 2 Zn(2+) ions per subunit. Inhibited by EDTA and EGTA in vitro. Homodimer; disulfide-linked (PubMed:26888014). Homotetramer (PubMed:26888014). Predominantly expressed in kidney with a lesser expression in brain and heart (PubMed:15788404, PubMed:26888014). In the brain and spinal cord, mainly expressed in the white matter. In oligodendrocytes, is predominantly detected in the myelin sheath. In the kidney, is predominantly expressed in the luminal side of the renal tubule in the cortex and in the proximal renal tubules. It is expressed in liver sinusoidal endothelial cells (PubMed:26888014). At postnatal day 2 (P2) and P4, is detected in immature oligodendrocytes, where it was predominantly found both in the processes and cell bodies. In contrast, at P12 and P14, it is found mainly in myelin sheaths. Enpp6 knockout mice give birth according to the Mendelian rule and are apparently normal. Mice exhibit mild symptoms of fatty liver and are more susceptible to a choline-deficient diet and exhibit severe fatty liver phenotypes at the early stage. Belongs to the nucleotide pyrophosphatase/phosphodiesterase family.