(A) Schematic diagram showing a bundle of three stereocilia protruding from a mammalian hair cell. The deflection of the stereocilia by sound waves results in the opening of the MET channels (pale blue cylinders) and the generation of an electrical signal that travels along sensory neurons to the brain. The motor protein myosin VIIa transports USH1 proteins to maintain the structural integrity of stereocilia. Figure adapted from Figure 1e, Richardson et al. (Richardson et al., 2011). (B) Flies use antennae made up of three segments to detect sound. The schematic diagram on the left shows the second segment: there are MET channels for each neuron (outlined in green) and myosin II and myosin VIIa are enriched at the tip of scolopale cells, where USH1 proteins, Ubr3 and Cul1 form a protein complex. A Pcdh15 protein in the USH1 complex anchors the tip of scolopale cell to the cap cell. When a sound wave hits the antenna, the joint between the second and the third segment is deflected (right panel) and the resultant stretching of the second segment opens the MET channels. This depolarizes the sensory neurons, causing them to signal to the brain. Figure adapted from Figure 1b, Boekhoff-Falk and Eberl (Boekhoff-Falk and Eberl, 2014).