A novel tachykinin-related peptide receptor of Octopus vulgaris--evolutionary aspects of invertebrate tachykinin and tachykinin-related peptide.
The tachykinin (TK) and tachykinin-related peptide (TKRP) family represent one of the largest peptide families in the animal kingdom and exert their actions via a subfamily of structurally related G-protein-coupled receptors. In this study, we have identified a novel TKRP receptor from the Octopus heart, oct-TKRPR. oct-TKRPR includes domains and motifs typical of G-protein-coupled receptors. Xenopus oocytes that expressed oct-TKRPR, like TK and TKRP receptors, elicited an induction of membrane chloride currents coupled to the inositol phosphate/calcium pathway in response to Octopus TKRPs (oct-TKRP I-VII) with moderate ligand selectivity. Substance P and Octopus salivary gland-specific TK, oct-TK-I, completely failed to activate oct-TKRPR, whereas a Substance P analog containing a C-terminal Arg-NH2 exhibited equipotent activation of oct-TKRPs. These functional analyses prove that oct-TKRPs, but not oct-TK-I, serve as endogenous functional ligands through oct-TKRPR, although both of the family peptides were identified in a single species, and the importance of C-terminal Arg-NH2 in the specific recognition of TKRPs by TKRPR is conserved through evolutionary lineages of Octopus. Southern blotting of RT-PCR products revealed that the oct-TKRPR mRNA was widely distributed in the central and peripheral nervous systems plus several peripheral tissues. These results suggest multiple physiologic functions of oct-TKRPs as neuropeptides both in the Octopus central nervous system and in peripheral tissues. This is the first report on functional discrimination between invertebrate TKRPs and salivary gland-specific TKs.
Kanda
Atsuhiro
A
Suntory Institute for Bioorganic Research, Osaka, Japan. kanda@sunbor.or.jp
Takuwa-Kuroda
Kyoko
K
Aoyama
Masato
M
Satake
Honoo
H
D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D049831:Octopodiformes / Q000737:chemistry* / Q000235:genetics; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D018039:Receptors, Tachykinin / Q000737:chemistry* / Q000235:genetics; D015320:Tachykinins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics
D010455:Peptides; D018039:Receptors, Tachykinin; D015320:Tachykinins; D029867:Xenopus Proteins