An extract of the whole brain of the frog Rana ridibunda contained high concentrations of substance P‐like immunoreactivity, measured with an antiserum directed against the COOH‐terminal region of mammalian substance p and neurokinin b‐like immurtoreactivity, measured with an antiserum directed against the NH2‐terminus of neurokinin B. The primary structure of the substance p‐related peptide (ranakinin) was established as: Lys‐Pro‐Asn‐Pro‐Glu‐Arg‐Phe‐Tyr‐Gly‐Leu‐Met‐NH2. Mammalian substance P was not present in the extract. The primary structure of the neurokinin b‐related peptide was established as: Asp‐Met‐His‐Asp‐Phe‐Phe‐Val‐Gly‐Leu‐Met‐NH2. This amino acid sequence is the same as that of mammalian neurokinin B. Ranakinin was equipotent with substance p and [Sar9,‐Met(O2)11]substance p in inhibiting the binding of 125I‐Bolton‐Hunter‐[Sar9, Met(O2)11]substance p, a selective radio‐ligand for the NK1 receptor, to binding sites in rat subman‐dibular gland membranes (IC50 1.6 ± 0.3 nM; n = 5). It is concluded that ranakinin is a preferred agonist for the mammalian NK1 tachykinin receptor subtype.
|Number of pages||6|
|Journal||Journal of Neurochemistry|
|Publication status||Published - Dec 1991|
- O'Harte F. et al. Ranakinin: A novel NK1 tachykinin receptor agonist isolated with neurokinin b from the brain of the frog Rana ridibunda.
- Tachykinin—Substance p—Neurokinin b—Frog brain