SLC34A1,2 cotransports Pi, 3Na+ from extracellular region to cytosol

Stable Identifier
Reaction [transition]
Homo sapiens
Electrogenic Na+/Pi cotransport
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SLC34A1 encodes Na+/Pi cotransporter (NaPi-IIa) which is expressed in the kidney in the renal proximal tubule (Magagnin et al. 1993). SLC34A2 encodes NaPi-IIb which is abundantly expressed in lung and to a lesser degree in tissues of epithelial origin including small intestine, pancreas, prostate, and kidney (Field et al. 1999). In the lung, SLC34A2 is expressed only in alveolar type II cells, which are responsible for surfactant production, so it is proposed that it uptakes liberated phosphate from the alveolar fluid for surfactant production. Both NaPi-IIa and NaPi-IIb cotransport inorganic phosphate (Pi) with three Na+ ions (electrogenic transport) (Forster et al. 1999, 2002).

Defects in SLC34A1 are the cause of hypophosphatemic nephrolithiasis/osteoporosis type 1 (NPHLOP1) (Prie et al. 2002). Defects in SLC34A2 are a cause of pulmonary alveolar microlithiasis, a rare disease characterised by the deposition of calcium phosphate microliths throughout the lung (Corut et al. 2006).
Literature References
PubMed ID Title Journal Year
16960801 Mutations in SLC34A2 cause pulmonary alveolar microlithiasis and are possibly associated with testicular microlithiasis

Corut, A, Tolun, A, Yildirim, Z, Gocmen, A, Senyigit, A, Ozcelik, U, Altin, S, Calisir, H, Ugur, SA

Am J Hum Genet 2006
12379267 Forging the link between structure and function of electrogenic cotransporters: the renal type IIa Na+/Pi cotransporter as a case study

Biber, J, Forster, IC, Murer, H, Köhler, K

Prog. Biophys. Mol. Biol. 2002
12324554 Nephrolithiasis and osteoporosis associated with hypophosphatemia caused by mutations in the type 2a sodium-phosphate cotransporter

Huart, V, Friedlander, G, Silve, C, Dellis, O, Planelles, G, Grandchamp, B, Bakouh, N, Gérard, B, Prie, D, Benqué-Blanchet, F, Hulin, P

N Engl J Med 2002
10329428 Cloning and functional characterization of a sodium-dependent phosphate transporter expressed in human lung and small intestine

Feild, JA, Brun, KA, Edwards, RM, Brooks, DP, Zhang, L

Biochem Biophys Res Commun 1999
8327470 Expression cloning of human and rat renal cortex Na/Pi cotransport

Stange, G, Sorribas, V, Werner, A, Magagnin, S, Markovich, D, Biber, J, Murer, H

Proc Natl Acad Sci U S A 1993
10198426 Stoichiometry and Na+ binding cooperativity of rat and flounder renal type II Na+-Pi cotransporters

Eskandari, S, Loo, DD, Forster, IC

Am. J. Physiol. 1999
Catalyst Activity

sodium:phosphate symporter activity of SLC34A1,2 [plasma membrane]

Orthologous Events
Cross References
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