InterPro domain: IPR001902

The SLC26A/SulP family is a large and ubiquitous family with members derived from archaea, bacteria, fungi, plants and animals. Many organisms including Bacillus subtilis, Synechocystis sp, Saccharomyces cerevisiae, Arabidopsis thaliana and Caenorhabditis elegans possess multiple SulP family paralogues. Many of these proteins are functionally characterised, and most are inorganic anion uptake transporters or anion:anion exchange transporters. Some transport their substrate(s) with high affinities, while others transport it or them with relatively low affinities [ 1 , 2 , 3 ].

SLC26A/SulP family proteins consist of N- and C- termini flanking a transmembrane domain thought to span the lipid bilayer 10-14 times. In most casses, the C-terminal cytoplasmic region includes a STAS (sulfate transporter and anti-sigma factor antagonist) domain [ 4 ].

Malfunctions in members of the SLC26A family of anion transporters are involved in three human diseases: diastrophic dysplasia/achondrogenesis type 1B (DTDST), Pendred's syndrome (PDS) and congenital chloride diarrhea (CLD). These proteins contain 12 transmembrane helices followed by a cytoplasmic STAS domain at the C terminus. The importance of the STAS domain in these transporters is illustrated by the fact that a number of mutations in PDS and DTDST map to it [ 5 ].

Proteins in this family include:

• Neurospora crassa sulphate permease II (gene cys-14).
• Yeast sulphate permeases (genes SUL1 and SUL2).
• Rat sulphate anion transporter 1 (SAT-1).
• Mammalian DTDST, a probable sulphate transporter which, in human, is involved in the genetic disease, diastrophic dysplasia (DTD).
• Sulphate transporters 1, 2 and 3 from the legume Stylosanthes hamata.
• Human pendrin (gene PDS), which is involved in a number of hearing loss genetic diseases.
• Human protein DRA (Down-Regulated in Adenoma).
• Soybean early nodulin 70.
• Escherichia coli hypothetical protein ychM.
• Caenorhabditis elegans hypothetical protein F41D9.5.

1. Molecular architecture and the structural basis for anion interaction in prestin and SLC26 transporters. Nat Commun 5, 3622
2. Structure of a SLC26 anion transporter STAS domain in complex with acyl carrier protein: implications for E. coli YchM in fatty acid metabolism. Structure 18, 1450-62
3. The SLC26 gene family of anion transporters and channels. Mol. Aspects Med. 34, 494-515
4. The STAS domain - a link between anion transporters and antisigma-factor antagonists. Curr. Biol. 10, R53-5