Aquaporin channel (AQP (for individual family members, e.g., AQP1, AQP4))

Aquaporin channels are a family of small, integral membrane proteins—classified as water channels—that form pores in biological cell membranes, facilitating fast and selective transport of water, and in some cases glycerol and other small solutes, down osmotic gradients[1][2][6]. Structurally, they are characterized by six transmembrane α-helices and a conserved Asn-Pro-Ala (NPA) motif, assembling as tetramers in cellular membranes with each monomer functioning independently as a pore[1][3][4][6]. The family contains water-specific aquaporins and aquaglyceroporins (which also conduct glycerol), with a signature “hourglass” fold that imparts strict selectivity for water (or water/glycerol) while excluding protons and ions[1][5][6]. Aquaporins play essential roles in physiological processes such as renal water reabsorption, brain fluid regulation, and glandular secretion. Dysregulation or mutation of specific aquaporins has been implicated in diseases ranging from congenital nephrogenic diabetes insipidus to brain edema and neuromyelitis optica[6]. While considered attractive therapeutic targets, especially for CNS or renal indications, the development of potent, specific aquaporin-modulating drugs remains an ongoing challenge[6].

Other names

water channelmajor intrinsic protein (MIP)aquaglyceroporin (for subsets)

Inhibition of water permeability (by blocking channel function or by reducing aquaporin membrane expression) Modulation of trafficking (regulating expression or localization in the membrane)