4gtw

Structural highlights

Disease

ENPP1_MOUSE Defects in Enpp1 are the cause of the tiptoe walking (ttw) phenotype. Ttw mice exhibit ossification of the spinal ligaments.^[1] ENPP2_MOUSE Note=May contribute to obesity.

Function

ENPP1_MOUSE Appears to modulate insulin sensitivity (By similarity). By generating PPi, plays a role in regulating pyrophosphate levels, and functions in bone mineralization and soft tissue calcification. PPi inhibits mineralization by binding to nascent hydroxyapatite (HA) crystals, thereby preventing further growth of these crystals. Preferentially hydrolyzes ATP, but can also hydrolyze other nucleoside 5' triphosphates such as GTP, CTP, TTP and UTP to their corresponding monophosphates with release of pyrophosphate and diadenosine polyphosphates, and also 3',5'-cAMP to AMP. May also be involved in the regulation of the availability of nucleotide sugars in the endoplasmic reticulum and Golgi, and the regulation of purinergic signaling.^{[2] [3]} ENPP2_MOUSE Hydrolyzes lysophospholipids to produce lysophosphatidic acid (LPA) in extracellular fluids. Major substrate is lysophosphatidylcholine. Also can act on sphingosylphosphphorylcholine producing sphingosine-1-phosphate, a modulator of cell motility. Can hydrolyze, in vitro, bis-pNPP, to some extent pNP-TMP, and barely ATP. Involved in several motility-related processes such as angiogenesis and neurite outgrowth. Acts as an angiogenic factor by stimulating migration of smooth muscle cells and microtubule formation. Stimulates migration of melanoma cells, probably via a pertussis toxin-sensitive G protein. May have a role in induction of parturition. Possible involvement in cell proliferation and adipose tissue development. Tumor cell motility-stimulating factor.^{[4] [5] [6]}

See Also

• Ectonucleotide pyrophosphatase/phosphodiesterase
• Ectonucleotide pyrophosphatase/phosphodiesterase 3D structures

References

1. ↑ Okawa A, Nakamura I, Goto S, Moriya H, Nakamura Y, Ikegawa S. Mutation in Npps in a mouse model of ossification of the posterior longitudinal ligament of the spine. Nat Genet. 1998 Jul;19(3):271-3. PMID:9662402 doi:http://dx.doi.org/10.1038/956
2. ↑ Rebbe NF, Tong BD, Finley EM, Hickman S. Identification of nucleotide pyrophosphatase/alkaline phosphodiesterase I activity associated with the mouse plasma cell differentiation antigen PC-1. Proc Natl Acad Sci U S A. 1991 Jun 15;88(12):5192-6. PMID:1647027
3. ↑ Okawa A, Nakamura I, Goto S, Moriya H, Nakamura Y, Ikegawa S. Mutation in Npps in a mouse model of ossification of the posterior longitudinal ligament of the spine. Nat Genet. 1998 Jul;19(3):271-3. PMID:9662402 doi:http://dx.doi.org/10.1038/956
4. ↑ Boucher J, Quilliot D, Praderes JP, Simon MF, Gres S, Guigne C, Prevot D, Ferry G, Boutin JA, Carpene C, Valet P, Saulnier-Blache JS. Potential involvement of adipocyte insulin resistance in obesity-associated up-regulation of adipocyte lysophospholipase D/autotaxin expression. Diabetologia. 2005 Mar;48(3):569-77. Epub 2005 Feb 8. PMID:15700135 doi:10.1007/s00125-004-1660-8
5. ↑ Pradere JP, Tarnus E, Gres S, Valet P, Saulnier-Blache JS. Secretion and lysophospholipase D activity of autotaxin by adipocytes are controlled by N-glycosylation and signal peptidase. Biochim Biophys Acta. 2007 Jan;1771(1):93-102. Epub 2006 Dec 6. PMID:17208043 doi:10.1016/j.bbalip.2006.11.010
6. ↑ Nishimasu H, Okudaira S, Hama K, Mihara E, Dohmae N, Inoue A, Ishitani R, Takagi J, Aoki J, Nureki O. Crystal structure of autotaxin and insight into GPCR activation by lipid mediators. Nat Struct Mol Biol. 2011 Feb;18(2):205-12. doi: 10.1038/nsmb.1998. Epub 2011 Jan, 16. PMID:21240269 doi:10.1038/nsmb.1998
7. ↑ Kato K, Nishimasu H, Okudaira S, Mihara E, Ishitani R, Takagi J, Aoki J, Nureki O. Crystal structure of Enpp1, an extracellular glycoprotein involved in bone mineralization and insulin signaling. Proc Natl Acad Sci U S A. 2012 Oct 16;109(42):16876-81. doi:, 10.1073/pnas.1208017109. Epub 2012 Oct 1. PMID:23027977 doi:http://dx.doi.org/10.1073/pnas.1208017109