Primary structure and receptor-binding properties of a neurokinin A-related peptide from frog gut

Y. Wang, T. Badgery-Parker, S. Lovas, N. Chartrel, H. Vaudry, E. Burcher, J. M. Conlon

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25 Citations (Scopus)


A tachykinin peptide was isolated from an extract of the intestine of the European green frog, Rana ridibunda, and its primary structure was established as:His-Lys-Leu-Asp-Ser-phe-Ile-Gly-Leu-Met.CONH2. This sequence was confirmed by chemical synthesis and shows two amino acid substitutions (leucine for threonine at position 3 and isoleucine for valine at position 7) compared with neurokinin A. Binding parameters for synthetic [Leu3,Ile7]neurokinin A and mammalian tachykinins were compared using receptor-selective radioligands and crude membranes from tissues enriched in the NK1, NK2 and NK3 receptors. [Leu3,Ile7]Neurokinin A was approx. 3-fold less potent than substance P in inhibiting the binding of 125I-labelled [Sar9,Met(O2)11]substance P (labelled with Bolton-Hunter reagent) to rat submandibular gland (NK1 receptor), 8-fold less potent than neurokinin A in inhibiting the binding of [2-[125I]iodohistidine(l)]neurokinin A to rat stomach fundus (NK2 receptor) and 6-fold less potent than neurokinin B in inhibiting the binding of 125I-Bolton-Hunter-labelled scyliorhinin II to rat brain (NK3 receptor). Thus the frog neurokinin A-related peptide shows moderate affinity but lack of selectively for all three tachykinin-binding sites in rat tissues. This non-selectivity is similar to that displayed by the molluscan tachykinin, eledoisin, which also contains an isoleucine residue in the corresponding position in the molecule.

Original languageEnglish
Pages (from-to)827-832
Number of pages6
JournalBiochemical Journal
Issue number3
Publication statusPublished (in print/issue) - 1992


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