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ENPP1/PC1

Domain

The di-leucine motif is required for basolateral targeting in epithelial cells, and for targeting to matrix vesicles derived from mineralizing cells.

Function

Nucleotide pyrophosphatase that generates diphosphate (PPi) and functions in bone mineralization and soft tissue calcification by regulating pyrophosphate levels (By similarity). PPi inhibits bone mineralization and soft tissue calcification by binding to nascent hydroxyapatite crystals, thereby preventing further growth of these crystals (PubMed:11004006). 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 (PubMed:27467858, PubMed:8001561, PubMed:25344812). 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 (PubMed:27467858, PubMed:8001561). Inhibits ectopic joint calcification and maintains articular chondrocytes by repressing hedgehog signaling; it is however unclear whether hedgehog inhibition is direct or indirect (By similarity). Appears to modulate insulin sensitivity and function (PubMed:10615944). Also involved in melanogenesis (PubMed:28964717). Also able to hydrolyze 2'-3'-cGAMP (cyclic GMP-AMP), a second messenger that activates TMEM173/STING and triggers type-I interferon production (PubMed:25344812). 2'-3'-cGAMP degradation takes place in the lumen or extracellular space, and not in the cytosol where it is produced; the role of 2'-3'-cGAMP hydrolysis is therefore unclear (PubMed:25344812). Not able to hydrolyze the 2'-3'-cGAMP linkage isomer 3'-3'-cGAMP (PubMed:25344812).

Involvement in disease

Ossification of the posterior longitudinal ligament of the spine

OPLL

A calcification of the posterior longitudinal ligament of the spinal column, usually at the level of the cervical spine. Patients with OPLL frequently present with a severe myelopathy that can lead to tetraparesis.

None

The disease is caused by variants affecting the gene represented in this entry.

Arterial calcification of infancy, generalized, 1

GACI1

A severe autosomal recessive disorder characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. The disorder is often fatal within the first 6 months of life because of myocardial ischemia resulting in refractory heart failure.

None

The disease is caused by variants affecting the gene represented in this entry.

Diabetes mellitus, non-insulin-dependent

NIDDM

A multifactorial disorder of glucose homeostasis caused by a lack of sensitivity to the body's own insulin. Affected individuals usually have an obese body habitus and manifestations of a metabolic syndrome characterized by diabetes, insulin resistance, hypertension and hypertriglyceridemia. The disease results in long-term complications that affect the eyes, kidneys, nerves, and blood vessels.

None

Disease susceptibility is associated with variants affecting the gene represented in this entry.

Hypophosphatemic rickets, autosomal recessive, 2

ARHR2

A hereditary form of hypophosphatemic rickets, a disorder of proximal renal tubule function that causes phosphate loss, hypophosphatemia and skeletal deformities, including rickets and osteomalacia unresponsive to vitamin D. Symptoms are bone pain, fractures and growth abnormalities.

None

The disease is caused by variants affecting the gene represented in this entry.

Cole disease

COLED

A rare autosomal dominant genodermatosis characterized by punctate keratoderma associated with irregularly shaped hypopigmented macules, which are typically found over the arms and legs but not the trunk or acral regions. Skin biopsies of palmoplantar lesions show hyperorthokeratosis, hypergranulosis, and acanthosis. Hypopigmented areas of skin, however, reveal a reduction in melanin content in keratinocytes but not in melanocytes, as well as hyperkeratosis and a normal number of melanocytes. Ultrastructurally, melanocytes show a disproportionately large number of melanosomes in the cytoplasm and dendrites, whereas keratinocytes show a paucity of these organelles, suggestive of impaired melanosome transfer. Some patients also exhibit calcinosis cutis or calcific tendinopathy.

None

The disease is caused by variants affecting the gene represented in this entry.

Post-translational modifications

Autophosphorylated as part of the catalytic cycle of phosphodiesterase/pyrophosphatase activity.

N-glycosylated.

The secreted form is produced through cleavage at Lys-103 by intracellular processing.

Sequence similarities

Belongs to the nucleotide pyrophosphatase/phosphodiesterase family.

Tissue specificity

Expressed in plasma cells and also in a number of non-lymphoid tissues, including the distal convoluted tubule of the kidney, chondrocytes and epididymis (PubMed:9344668). Expressed in melanocytes but not in keratinocytes (PubMed:28964717).

Cellular localization

  • Ectonucleotide pyrophosphatase/phosphodiesterase family member 1
  • Cell membrane
  • Single-pass type II membrane protein
  • Basolateral cell membrane
  • Single-pass type II membrane protein
  • Targeted to the basolateral membrane in polarized epithelial cells and in hepatocytes, and to matrix vesicles in osteoblasts (PubMed:11598187). In bile duct cells and cancer cells, located to the apical cytoplasmic side (PubMed:11598187).
  • Ectonucleotide pyrophosphatase/phosphodiesterase family member 1, secreted form
  • Secreted
  • Secreted following proteolytic cleavage.

Alternative names

  • Ectonucleotide pyrophosphatase/phosphodiesterase family member 1
  • E-NPP 1
  • Membrane component chromosome 6 surface marker 1
  • Phosphodiesterase I/nucleotide pyrophosphatase 1
  • Plasma-cell membrane glycoprotein PC-1
  • M6S1
  • PDNP1
  • PC1
  • NPPS
  • ENPP1

Target type

Proteins

Molecular weight

104924Da