Defective SLC34A2 does not cotransport HPO4(2-), 3Na+ from extracellular region to cytosol

Stable Identifier
Reaction [transition]
Homo sapiens
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The human gene SLC34A2 encodes NaPi-2b which is abundantly expressed in lung and to a lesser degree in epithelia of other tissues including small intestine, pancreas, prostate, and kidney. 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. SLC34A2 cotransports divalent phosphate (HPO4(2-)) with three Na+ ions (electrogenic transport) from the extracellular region into alveolar type II cells. Defects in SLC34A2 can cause pulmonary alveolar microlithiasis (PALM; MIM:265100), a rare disease characterised by the deposition of calcium phosphate microliths (tiny, roundish corpuscles) throughout the lung. Most patients remain asymptomatic for years or decades, the disease following a long-term, progressive course resulting in slow deterioration of lung functions. Mutations leading to PALM include Q76*, G106R, V448*, K304* and Q486* (Corut et al. 2006, Yin et al. 2013, Proesmans et al. 2012).

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
23164546 SLC34A2 Gene mutation of pulmonary alveolar microlithiasis: report of four cases and review of literatures

Shao, J, Wu, D, Zhao, G, Wang, H, Dai, Y, Yin, X

Respir Med 2013
22311166 Pulmonary alveolar microlithiasis: a case report and review of the literature

De Boeck, K, Verbeken, E, Boon, M, Ozcelik, U, Van de Casseye, W, Kiper, N, Proesmans, M

Eur. J. Pediatr. 2012
Catalyst Activity

sodium:phosphate symporter activity of SLC34A2 mutants [plasma membrane]

Normal reaction
Functional status

Loss of function of SLC34A2 mutants [plasma membrane]

Name Identifier Synonyms
pulmonary alveolar microlithiasis DOID:12117 pulmonary alveolar microlithiasis (disorder)
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