Shibahara M, Sakurai T, Nambu T, Takenouchi T, Iwaasa H, Egashira S I, Ihara M, Goto K
Institute of Basic Medical Sciences, University of Tsukuba, Ibaraki, Japan.
Peptides. 1999;20(10):1169-76. doi: 10.1016/s0196-9781(99)00120-5.
We isolated the Xenopus gene encoding prepro-orexin to predict the structures of orexins in submammalian chordates. Putative mature Xenopus orexin-A and -B are highly similar to each mammalian counterpart. Especially, the C-terminal 10 residues were highly conserved among these species and isopeptides. Immunohistochemical examination of Xenopus brain revealed that orexin-containing neurons were highly specifically localized in the ventral hypothalamic nucleus. A rich network of immunoreactive fibers was found in various regions of the Xenopus brain. The distribution was similar to that of mammalian orexins. Xenopus orexin-A and -B specifically bind and activate human orexin receptors expressed in Chinese hamster ovary cells. Of interest, Xenopus orexin-B had several-fold higher affinity to human OX2R compared with human orexins. These results suggest that Xenopus orexin-B might be a useful pharmacological tool as an OX2R selective high-affinity agonist.
