SLC4A4

Electrogenic sodium bicarbonate cotransporter 1 is a is_associated_with::membrane transport protein that in humans is encoded by the SLC4A4 is_associated_with::gene.

Function
Sodium bicarbonate is_associated_with::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 cotransport is involved in bicarbonate secretion/absorption and is_associated_with::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]

Clinical significance
NBCe1 may participate in regulation of brain is_associated_with::extracellular space is_associated_with::pH. Some mutations in NBCe1 have been associated with is_associated_with::Familial hemiplegic migraine. Other NBCe1 mutations disrupt kidney bicarbonate transport and cause is_associated_with::proximal renal tubular acidosis.

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.