Which of the following is a mechanically gated ion channel?
Mechanically gated ion channels convert physical deformation stretch pressure into electrical signals essential for touch hearing proprioception vascular tone and volume control. Stretch-activated cation channels in dorsal root sensory neurons including Piezo1 and Piezo2 giant proteins over thirty transmembrane helices propeller blades and TRP members like TRPV4 contain large curved domains acting as membrane tension sensors coupled to central pore. Increased lateral tension or cytoskeletal pulling flattens protein expanding fenestrations opening pore permeable to Na+ K+ Ca2+ generating receptor potential depolarizing nerve ending triggering action potentials when threshold reached encoding light touch vibration proprioception and painful pressure. In auditory hair cells tip links protocadherin 15 cadherin 23 pull directly open transduction channels upon stereocilia deflection. These channels respond to mechanical deformation rather than voltage change sensed by S4 arginines or chemical ligand binding extracellular domain though lipids pH phosphorylation tune sensitivity. Nicotinic acetylcholine receptor is ligand-gated pentamer neuronal sodium channel Nav1.7 is voltage-gated four domain and GLUT2 is facilitative MFS glucose carrier not ion channel lacking mechanosensitive architecture.
Ref: Ranade et al., Nature 2015: Piezo Proteins as Mechanically-Gated Stretch Channels.