Electrogenic sodium bicarbonate cotransporter 1

Electrogenic sodium bicarbonate cotransporter 1, sodium bicarbonate cotransporter is a membrane transport protein that in humans is encoded by the SLC4A4 gene.^[5][6][7]

SLC4A4
Identifiers
Aliases	SLC4A4, HNBC1, KNBC, NBC1, NBC2, NBCe1-A, SLC4A5, hhNMC, pNBC, kNBC1, solute carrier family 4 member 4
External IDs	OMIM: 603345; MGI: 1927555; HomoloGene: 55776; GeneCards: SLC4A4; OMA:SLC4A4 - orthologs
Gene location (Human) Chr. Chromosome 4 (human)[1] Band 4q13.3 Start 71,186,757 bp[1] End 71,572,087 bp[1]
Gene location (Mouse) Chr. Chromosome 5 (mouse)[2] Band 5|5 E1 Start 89,034,345 bp[2] End 89,387,512 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in jejunal mucosa external globus pallidus mucosa of sigmoid colon pancreatic ductal cell internal globus pallidus kidney tubule body of pancreas dorsal motor nucleus of vagus nerve duodenum bronchial epithelial cell Top expressed in ciliary body cerebellar vermis deep cerebellar nuclei human kidney lobe of cerebellum globus pallidus dorsal tegmental nucleus right kidney medial vestibular nucleus iris More reference expression data BioGPS More reference expression data
Gene ontology Molecular function transporter activity anion transmembrane transporter activity protein binding symporter activity inorganic anion exchanger activity sodium:bicarbonate symporter activity identical protein binding Cellular component integral component of membrane plasma membrane basolateral plasma membrane integral component of plasma membrane extracellular exosome membrane Biological process bicarbonate transport anion transmembrane transport anion transport sodium ion transport sodium ion transmembrane transport ion transport inorganic anion transport regulation of intracellular pH transmembrane transport transport Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 8671 54403 Ensembl ENSG00000080493 ENSMUSG00000060961 UniProt Q9Y6R1 O88343 RefSeq (mRNA) NM_001098484 NM_001134742 NM_003759 NM_001136260 NM_001197147 NM_018760 NM_001359211 NM_001359212 NM_001359213 RefSeq (protein) NP_001091954 NP_001128214 NP_003750 NP_001129732 NP_001184076 NP_061230 NP_001346140 NP_001346141 NP_001346142 Location (UCSC) Chr 4: 71.19 – 71.57 Mb Chr 5: 89.03 – 89.39 Mb PubMed search [3] [4]
Wikidata
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Function

Sodium bicarbonate cotransporters (NBCs) mediate the coupled movement of sodium and bicarbonate ions across the plasma membrane of many cells. This is an electrogenic process with an apparent stoichiometry of 3 bicarbonate ions per sodium ion. Sodium bicarbonate co-transport is involved in bicarbonate secretion/absorption and intracellular pH regulation. Romero and Boron (1999) reviewed NBCs. Soleimani and Burnham (2000) reviewed NBCs and their regulation in physiologic and pathophysiologic states.[supplied by OMIM]^[7]

Clinical significance

In the brain, the sodium bicarbonate transporter is predominantly expressed by astrocytes.^[8] They may participate in regulation of brain extracellular space pH.^[9] Some mutations in the gene have been associated with familial hemiplegic migraine.^[10] Other mutations disrupt kidney bicarbonate transport and cause proximal renal tubular acidosis.^[11]

Splice variants

NBCe1-A aka kNBC1 (mainly expressed in the kidney)

NBCe1-B aka pNBC1 (expressed in the pancreas and elsewhere)

NBCe1-C (expressed in the brain)

Distribution

The renal SLC4A4 gene product NBCe1-A is specifically expressed in the basolateral membranes of proximal tubule epithelia.

See also

• Solute carrier family