Neurokinin A acts via neurokinin 2 (NK-2) receptor.
Neurokinin A (substance K) is a peptide neurotransmitter of the tachykinin family with potential as a major mediator in human airway and gastrointestinal tissues. Neurokinin A acts via the NK-2 receptor believed to be localized on smooth muscle cells and pharmacologically coupled to a GTP-binding protein. Neurokinin A is a member of a family of peptide neurotransmitters known as tachykinins. These peptides are associated with the central and peripheral nervous systems and display a wide tissue distribution. Tachykinins share the COOH-terminal structure Phe-X-Gly-Leu-Met-NH. The best known members of this family are Substance P and Neurokinin A or Substance K[1].
References:
[1]. Gerard NP, et al. The human neurokinin A (substance K) receptor. Molecular cloning of the gene, chromosome localization, and isolation of cDNA from tracheal and gastric tissues. J Biol Chem. 1990 Nov 25;265(33):20455-62.