OTOP1 protein

1. Japanese scientist Kikunae Ikeda first proposed umami as a basic taste in addition to sweet, sour, salty and bitter which was officially agreed the scientific community after 80 years.
2. Now, it has been found that the tongue responds to ammonium chloride (salmiak salt), which has been recognised as a 6th basic sense.
3. The tongue responds to the same protein receptor that signals sour taste while responding to ammonium chloride.
4. OTOP1 is a protein present within cell membranes and forms a channel for hydrogen ions moving into the cell and is responsible for detecting sour taste.
5. OTOP1 responds to the salt, generating an electrical signal in taste bud cells.