(redirected from TK)
Also found in: Dictionary, Financial, Acronyms, Encyclopedia, Wikipedia.


Any member of a group of polypeptides, widely scattered in vertebrate and invertebrate tissues, which have in common four of the five terminal amino acids: Phe-Xaa-Gly-Leu-Met-NH2; pharmacologically, they all cause hypotension in mammals, contraction of gut and bladder smooth muscle, and secretion of saliva.
[G. tachys, swift, + kineō, to move, + -in]
Farlex Partner Medical Dictionary © Farlex 2012


(tăk″kī′nĭn) [″ + ″],


Any of a large family of peptides that function as neurotransmitters in the central and peripheral nervous systems. They have extraneuronal activity in other body tissues. Their diverse biological actions are mediated through cellular G proteins.
Medical Dictionary, © 2009 Farlex and Partners