Aquaporin‑1 (AQP1)

Aquaporin‑1 is a tetrameric integral membrane protein, with each monomer comprising six transmembrane α-helices connected by five loops (two extracellular, three intracellular), and containing the highly conserved asparagine-proline-alanine (NPA) motifs responsible for water selectivity[1][2][4][6][3][7]. It is found in erythrocytes, kidney, vascular endothelium, and the central nervous system, facilitating rapid osmotic water flux and contributing critically to fluid balance in mammals. The channel operates via a single-file water transport mechanism with size-exclusion selectivity, preventing proton and ion leakage[2][6][7]. In some cases, the central pore of the tetramer may exhibit limited ion conductance[2][4]. Aquaporin‑1’s activity can be modulated by small molecules and post-translational modifications, providing possible avenues for therapeutic intervention in diseases linked to abnormal water transport[5][1]. In summary: Aquaporin‑1 (AQP1) is a prototypical water channel protein, playing vital roles in physiology and disease, and remains a focus of therapeutic research for managing water balance disorders.

Other names

CHIP28 (Channel-like integral membrane protein 28 kDa)Colton blood group antigen

Inhibitors block water permeability by interacting with cysteine residues near the pore (Cys-189), such as mercurials