Hemokinins and endokinins.
The mammalian tachykinins are a family of peptides that, until recently, has included substance P (SP), neurokinin A and neurokinin B. Since, the discovery of a third preprotachykinin gene ( TAC4), the number of tachykinins has more than doubled to reveal several species-divergent peptides. This group includes hemokinin-1 (HK-1) in mouse and rat, endokinin-1 (EK-1) in rabbit, and EKA, EKB, human HK-1 (hHK-1) and hHK(4-11) in humans. Each exhibits a remarkable selectivity and potency for the tachykinin NK(1) receptor similar to SP. Their peripheral expression has led to the proposal that they are the endogenous peripheral SP-like endocrine/paracrine agonists where SP is not expressed. Moreover, their strong cross-reactivity with a specific SP antibody leads us to question many of the proposed locations and roles of SP in the periphery. Additionally, three orphan tachykinin gene-related peptides are identified on TAC4, in rabbit, EK-2 and in humans, EKC and EKD.
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School of Animal and Microbial Sciences, The University of Reading, RG6 6AJ Reading, United Kingdom. sasnpage@reading.ac.uk
D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D011498:Protein Precursors / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D018039:Receptors, Tachykinin / Q000378:metabolism; D015320:Tachykinins / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D011498:Protein Precursors; D012333:RNA, Messenger; D018039:Receptors, Tachykinin; D015320:Tachykinins; C044206:preprotachykinin