Otopetrin 1 (OTOP1)

Otoconia are biominerals within the utricle and saccule of the inner ear that are critical for the perception of gravity and linear acceleration. The classic mouse mutant 'tilted' (tlt) and the allelic mouse mutant 'mergulhador' (mlh) are recessive mutations that affect balance by impairing otoconial morphogenesis without causing collateral deafness. The predicted multitransmembrane domain protein is expressed in the macula of the developing otocyst of the inner ear as well as in thymus, heart, kidney, skin, stomach, adrenal gland, and lactating mammary gland. The deduced 612-amino acid protein shares 77% sequence identity with the mouse protein. Otop1 is detectable in murine macular sensory epithelia; its protein product, otopetrin, is incorporated into the gelatinous membrane within the utricle and saccule, along with otoconin.