Otop1, also known as Otopetrin 1, is a proton-selective ion channel with crucial biological functions. It is involved in multiple sensory processes, such as sour taste sensation, ammonium chloride taste detection, and may participate in alkaline sensation in vertebrates. In the taste system, it is expressed in sour (Type III) taste receptor cells (TRCs) and is essential for sour sensing [1,2]. It also plays a role in the formation of otoconia in the inner ear [3].

Knockout studies have significantly enhanced our understanding of Otop1's functions. In Otop1 -/- mouse strains, taste responses to NH4Cl measured from isolated Type III TRCs or gustatory nerves were strongly attenuated or eliminated, revealing its role in mediating a major component of the taste of NH4Cl [1]. Additionally, knockout of Otop1 eliminated acid responses from sour-sensing taste receptor cells (TRCs), demonstrating its essentiality in sour sensing [2].

In conclusion, Otop1 is a multifunctional proton-selective ion channel. Model-based research, especially the use of Otop1 KO mouse models, has clearly shown its importance in taste-related sensory functions, including sour and ammonium chloride taste perception. These findings contribute to our understanding of taste transduction mechanisms and potentially related taste-associated disorders.

References:

1. Liang, Ziyu, Wilson, Courtney E, Teng, Bochuan, Kinnamon, Sue C, Liman, Emily R. 2023. The proton channel OTOP1 is a sensor for the taste of ammonium chloride. In Nature communications, 14, 6194. doi:10.1038/s41467-023-41637-4. https://pubmed.ncbi.nlm.nih.gov/37798269/

2. Zhang, Jin, Jin, Hao, Zhang, Wenyi, Ye, Mingyu, Zuker, Charles S. 2019. Sour Sensing from the Tongue to the Brain. In Cell, 179, 392-402.e15. doi:10.1016/j.cell.2019.08.031. https://pubmed.ncbi.nlm.nih.gov/31543264/

3. Islam, Md Mominul, Sasaki, Omi, Yano-Nashimoto, Saori, Okamatsu-Ogura, Yuko, Yamaguchi, Soichiro. 2023. Cibacron blue 3G-A is a novel inhibitor of Otopetrin 1 (OTOP1), a proton channel. In Biochemical and biophysical research communications, 665, 64-70. doi:10.1016/j.bbrc.2023.04.112. https://pubmed.ncbi.nlm.nih.gov/37149984/