The troubled story of tachykinins and neurokinins

A family of peptides that shares a common C-terminal sequence (Phe-X-Gly-Le u-MetNH(2)) exists in mammalian and non-mammalian species. In mammals, thre e of these peptides (substance P, neurokinin A and neurokinin B) satisfy th e criteria to be considered as neurotransmitters either in the central, per ipheral or enteric nervous systems. In addition, multiple receptors for the se peptides, which belong to the superfamily of G-protein-coupled receptors , exist. These receptors have distinct pharmacological features and selecti ve agonists and antagonists are available far studying their functional rol es. The latest update on nomenclature of these peptides and their receptors , which dates back to 1986, agreed to use the terms tachykinins and tachyki nin NK,, NK, and NK, receptors. This 'nomenclature mismatch' has generated confusion that urges experts in the field of tachykinin research to provide a revised nomenclature.