Structural physiology of distinctive water channels elucidated by cryo-EM

Aquaporins (AQPs) are membrane channel proteins that facilitate the transport of water and related solutes, playing indispensable roles across a wide range of organisms. Extensive structural studies using X-ray crystallography and electron crystallography have provided fundamental insights into the physiological functions of various AQPs. Recent advances in the structural analysis using single-particle cryo-electron microscopy, which bypasses the requirement for crystallization, have profoundly enhanced our understanding of AQP mechanisms. In this review, we summarize recent progress in AQP biology, providing a comparative analysis of orthodox, glycerol-permeable and unorthodox AQPs.