SLC26A11

Model summary

A human multi-pass anion transporter that uses a membrane-embedded SLC26/SulP core to exchange chloride, iodide, and other inorganic anions across the cell surface, thereby supporting epithelial fluid secretion and systemic anion balance. A cytosolic regulatory tail coordinates assembly and trafficking of the transporter through the secretory pathway and endocytic routes, enabling dynamic control at the plasma membrane and transient residence in biosynthetic and vesicular compartments.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The N-terminal two-thirds of the protein is defined by IPR011547 (SLC26A/SulP transporter domain, residues 48–441) embedded within the broader family signature IPR001902 (SLC26A/SulP transporter, residues 24–580). This arrangement establishes a canonical SLC26/SulP anion-transport core that forms multiple transmembrane helices to move inorganic anions across membranes. Within this core sits IPR018045 (Sulphate anion transporter, conserved site, residues 77–98), a hallmark motif that stabilizes anion coordination and exchange chemistry. Following the transmembrane core, the C-terminal cytosolic region contains IPR002645 (STAS domain, residues 471–576), encompassed by IPR036513 (STAS domain superfamily, residues 466–586). The STAS module typically couples transporter gating and trafficking to cytosolic regulatory partners. The ordered layout—transport core (24–441) feeding into a regulatory STAS tail (466–586)—causally specifies a multi-pass anion exchanger that is tuned by cytosolic protein interactions.

2. 02

   This architecture dictates molecular function.

   The SLC26/SulP core and the sulfate-transporter conserved site together impose an anion-translocation mechanism that accommodates monovalent and divalent anions. Such a mechanism directly supports GO:0015116 sulfate transmembrane transporter activity and more generally GO:0008509 monoatomic anion transmembrane transporter activity. The prominent STAS domain and extended cytosolic tail create docking surfaces for regulatory proteins, accounting for GO:0005515 protein binding as an intrinsic property necessary for assembly and control of the transporter complex.

3. 03

   From function to process, sustained anion exchange by this transporter drives epithelial and cellular anion homeostasis.

   The ability to move chloride, bromide, iodide, and sulfate through the SLC26/SulP core situates the protein squarely in GO:0006811 monoatomic ion transport. Its sulfate-transport competence and conserved site further anchor it in GO:0008272 sulfate transport, consistent with roles in epithelial fluid secretion and systemic anion balance.

4. 04

   Cellular location follows from the membrane-embedded transporter core and the trafficking cues in the STAS domain.

   The multi-pass topology and secretory pathway signatures place the protein at the GO:0005886 plasma membrane, where it mediates transmembrane anion exchange. Biosynthetic routing and quality control through the secretory pathway explain residence in the GO:0005783 endoplasmic reticulum and GO:0005794 Golgi apparatus. Packaging into extracellular vesicles is consistent with its membrane residency and turnover, aligning with GO:0070062 extracellular exosome. Occasional detection in the GO:0005654 nucleoplasm can be rationalized by transient trafficking or regulatory pools of the cytosolic STAS tail that interface with nuclear-proximal signaling; while not a primary site, it is compatible with dynamic regulatory cycles.

5. 05

   Mechanistically, the SLC26/SulP transmembrane core forms an anion-exchange pathway that couples conformational changes to substrate gradients, while the STAS domain recruits cytosolic partners that tune transport capacity and surface stability.

   This design predicts interactions with scaffolds and regulatory proteins that coordinate epithelial anion secretion and endocytic recycling. I hypothesize that the transporter assembles with PDZ-domain scaffolds and cytosolic adaptors to stabilize at the plasma membrane and with trafficking machinery in the ER–Golgi–endosome axis. In epithelia, it likely partners with other anion pathways to support fluid secretion and iodide handling, with the STAS domain acting as the regulatory hub that senses and relays protein–protein interactions to modulate transport efficiency.