SLC4 family of bicarbonate transporter (SLC4)

The **SLC4 family of bicarbonate transporter** (abbreviated **SLC4**) consists of multiple integral membrane proteins mediating the transport of bicarbonate (HCO₃⁻), chloride (Cl⁻), sodium (Na⁺), and carbonate (CO₃²⁻) across plasma membranes[1][2][4]. This family includes both **anion exchangers** (typically exchanging Cl⁻ and HCO₃⁻, such as AE1–3, and AE4) and **sodium-coupled bicarbonate cotransporters** (such as NBCe1, NBCe2, NBCn1, NBCn2, and NDCBE), which may be electroneutral or electrogenic depending on their stoichiometry[1][2][5][6]. SLC4 proteins are critical for **systemic and cellular pH regulation**, homeostasis of acid-base balance, and play vital roles in processes like **neutralization of gastric acid, renal acid-base transport, CO₂ carriage by red blood cells**, and **mineralization in calcifying cells**. Genetic and functional alterations in these transporters are linked to a range of **human diseases**, including **metabolic acidosis, renal tubular acidosis, cardiovascular and neurological conditions**, as well as disorders of biomineralization[2][4][5][7]. The family is a pharmacological target mainly for research, with **DIDS** and related stilbene derivatives being the principal inhibitors used experimentally. Most SLC4 proteins are composed of 10–14 predicted transmembrane segments and often function as dimers or higher-order oligomers[1][3].

Other names

Solute carrier family 4Bicarbonate transporter familyAnion exchanger family (includes AE1, AE2, AE3, AE4)Sodium bicarbonate cotransporter family (includes NBCe1, NBCe2, NBCn1, NBCn2, NDCBE)Bicarbonate transporters

Inhibition of ion transport (e.g., DIDS inhibits Cl⁻/HCO₃⁻ exchange) Modulation of acid-base transport and cellular pH via altered ion exchange or cotransport