Cloning and activation of the bullfrog apelin receptor: Gi/o coupling and high affinity for [Pro1]apelin-13

Mi Jin Moon, Dayoung Oh, Jung Sun Moon, Dong Ki Kim, Jong Ik Hwang, Ju Yeon Lee, Jae Il Kim, Sehyung Cho, Hyuk Bang Kwon, Jae Young Seong

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


In mammals, apelin and its G protein-coupled receptor, APJ, regulate blood pressure, intake of food and water, and cardiac contractility. In this study, we report the cloning and functional characterization of APJ in the bullfrog, Rana catesbeiana. Bullfrog APJ (bfAPJ) cDNA contains an open reading frame of 1083 nucleotides encoding a protein of 360 amino acid residues. Sequence alignment reveals 75% amino acid identity with Xenopus, 63% identity with zebrafish and 40-42% identity with mammalian APJs. RT-PCR analysis and tissue binding assay reveal high expression of bfAPJ mRNA in the brain, particularly in the hypothalamus, and moderate expression in the pituitary, testis, adrenal gland and lung. Whereas [pGlu1]apelin-13 did not induce CRE-luc (protein kinase A-specific reporter) and SRE-luc (protein kinase C-specific reporter) activity in cells expressing bfAPJ, this apelin-13 decreased forskolin-induced CRE-luc activity and cAMP accumulation in a pertussis toxin-sensitive manner. This study indicates that bfAPJ may couple to Gi/o. [Pro1]apelin-13, a synthetic apelin based on the sequence of the putative apelin gene from many non-mammalian species, activates bfAPJ with 5-10-fold greater sensitivity/affinity than mammalian apelin-13. Collectively, this study expands our understanding of the physiological roles of this receptor system in non-mammalian species.

Original languageEnglish (US)
Pages (from-to)51-60
Number of pages10
JournalMolecular and Cellular Endocrinology
Issue number1-2
StatePublished - Oct 15 2007


  • APJ
  • Apelin
  • Bullfrog
  • G
  • GPCR

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology


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