Sodium-dependent phosphate transport protein 2A

Sodium-dependent phosphate transport protein 2A, also known as Na⁺-P_i cotransporter 2a (NaPi-2a), is a protein in humans that is encoded by the SLC34A1 gene.^[5] This gene encodes a member of the type II sodium-phosphate cotransporter family.

SLC34A1
Identifiers
Aliases	SLC34A1, NPT2, NPTIIa, solute carrier family 34 member 1, NaPi-2a, HCINF2, SLC17A2, SLC11, NAPI-3, FRTS2, NPHLOP1
External IDs	OMIM: 182309; MGI: 1345284; HomoloGene: 20663; GeneCards: SLC34A1; OMA:SLC34A1 - orthologs
Gene location (Human) Chr. Chromosome 5 (human)[1] Band 5q35.3 Start 177,379,235 bp[1] End 177,398,848 bp[1]
Gene location (Mouse) Chr. Chromosome 13 (mouse)[2] Band 13 B1|13 29.81 cM Start 55,546,000 bp[2] End 55,563,405 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in kidney tubule metanephric glomerulus renal medulla right lobe of liver human kidney granulocyte blood mucosa of esophagus tonsil zone of skin Top expressed in right kidney human kidney proximal tubule clavicle membranous bone maxilla mandible lumbar subsegment of spinal cord rib primary visual cortex More reference expression data BioGPS n/a
Gene ontology Molecular function protein homodimerization activity protein binding symporter activity sodium:phosphate symporter activity PDZ domain binding protein-containing complex binding Cellular component integral component of membrane endosome membrane intrinsic component of plasma membrane integral component of plasma membrane cell surface brush border membrane perinuclear region of cytoplasm membrane raft vesicle brush border cytoplasm plasma membrane apical plasma membrane nuclear speck mitotic spindle Biological process phosphate ion transport response to potassium ion response to estradiol cellular response to staurosporine glycoprotein metabolic process response to cadmium ion ossification sodium-dependent phosphate transport positive regulation of phosphate transmembrane transport kidney development response to nutrient sodium ion transport response to thyroid hormone response to peptide hormone phosphate ion homeostasis response to magnesium ion dentinogenesis response to peptide response to vitamin A indole metabolic process cellular response to metal ion response to parathyroid hormone response to lead ion tricarboxylic acid metabolic process gentamycin metabolic process response to growth hormone arsenate ion transmembrane transport response to mercury ion cellular response to parathyroid hormone stimulus positive regulation of sodium-dependent phosphate transport positive regulation of membrane potential protein homooligomerization cellular phosphate ion homeostasis sodium ion transmembrane transport ion transport phosphate ion transmembrane transport sodium ion import across plasma membrane Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 6569 20505 Ensembl ENSG00000131183 ENSMUSG00000021490 UniProt Q06495 Q7Z725 Q60825 Q9D2V6 RefSeq (mRNA) NM_001167579 NM_003052 NM_011392 RefSeq (protein) NP_001161051 NP_003043 NP_003043.3 NP_035522 Location (UCSC) Chr 5: 177.38 – 177.4 Mb Chr 13: 55.55 – 55.56 Mb PubMed search [3] [4]
Wikidata
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Function

The sodium/phosphate cotransporter is a protein found in the proximal tubule of the nephron. It is responsible for reabsorbing approximately 80% of the phosphate that has been filtered out at the glomerulus. The transporter moves hydrogen phosphate (HPO₄²⁻) into the cell along with 3 sodium ions. Alternatively it can move dihydrogen phosphate (H₂PO₄⁻ along with 2 sodium ions. For both movements the net charge is +1. Once inside the cell hydrogen phosphate and dihydrogen phosphate may react with water to form each other. Transport of these chemicals out of the cell at the basolateral surface is not understood currently.^[6]

The NaPi channels are regulated by parathyroid hormone (PTH). PTH acts to decrease phosphate reabsorption from the renal filtrate and therefore promote its excretion into the urine. It does this by causing for endocytosis of NaPi transporters on the apical surface of the cell. With less transporter available more phosphate is lost in the urine.^[6]

Clinical significance

Mutations in this gene are associated with hypophosphatemia nephrolithiasis/osteoporosis 1.^[5]

See also

• Renal physiology
• Cotransporter
• Co-transport
• P-loop
• Solute carrier (SLC) family