Structural domains associated with permeation, gating and selectivity of Aquaporin ion channels found across phyla

Aquaporins (AQPs) are an ancient group of channels that arose early in phylogeny and radiated throughout the kingdoms of life. Classified as members of the broad Membrane Intrinsic Protein family, AQPs originally were envisioned as strictly water pores that were constitutively open. International research interest is driving new views of AQPs as multi-functional channels with complex control mechanisms that enable adaptive responses to physiological challenges. Expanding numbers of AQP classes are being discovered to allow permeation of diverse solutes in parallel to the archetypal substrate water, with channel activities that show subtype-specific regulation by intracellular and extracellular signals. To date, at least fifteen classes of AQPs from mammals, plants, insects and algae have been proposed to carry ions, enabling amino acid sequence comparisons that suggest ion channel functional domains arise from conserved transmembrane, loop and teminal regions of the tetrameric AQP protein, serving as selectivity filters, gates, and sites for modulation. More AQP ion channel classes likely await discovery, pending identification of relevant activators. Subtype-specific control of dual water-and-ion AQP classes orchestrate diverse roles for AQPs across the domains of life, promoting homeostasis, cell motility, nutrient acquisition, redox protection, sensory detection, and intercellular signaling in cells and tissues.

Source: arXiv:2608.10440v1 - http://arxiv.org/abs/2608.10440v1 PDF: https://arxiv.org/pdf/2608.10440v1 Original Link: http://arxiv.org/abs/2608.10440v1