There are three known mammalian tachykinin receptors termed NK<sub>1</sub>, NK<sub>2</sub> and NK<sub>3</sub>. All are members of the 7 transmembrane G-protein coupled receptor family and induce the activation of phospholipase C, producing inositol triphosphate (so called G<sub>q</sub>-coupled).
Inhibitors of NK-1, known as NK-1 receptor antagonists, can be used as antiemetic agents, such as the drug aprepitant.
The genes and receptor ligands are as follows:
(Hökfelt et al., 2001; Page, 2004; Pennefather et al., 2004; Maggi, 2000)