We have recently identified apelin as the endogenous ligand for human APJ. In rats, the highest expression of APJ mRNA was detected in the lung, suggesting that APJ and its ligand play an important role in the pulmonary system. When apelin-36 and its pyroglutamylated C-terminal peptide, [<Glu65]apelin-13, were compared in microphysiometric analyses, the elevation of extracellular acidification induced in cells expressing APJ by [<Glu65]apelin-13 was transient, whereas that by apelin-36 was sustained. These responses were almost completely inhibited by a specific inhibitor for Gi or that for Na+/H+ exchanger. 125I -Labeled [<Glu65]apelin-13 analogue specifically bound to APJ with a high affinity, and [<Glu65]apelin-13 was more potent than apelin-36 in competitive inhibition assays. Because pretreatment with apelin-36 but not [<Glu65]apelin-13 drastically reduced the binding of the labeled apelin to APJ, the different patterns of acidification induced by these two peptides appeared to reflect their dissociation rather than association with APJ. Apelin elicited the migration of APJ-expressing cells, and [<Glu65]apelin-13 was more potent than apelin-36 in this activity. Heterogeneous molecular forms of apelin corresponding to apelin-36 and [<Glu65]apelin-13 were produced in bovine colostrum. Apelin-36 and [<Glu65]apelin-13 might have different functions in vivo and in vitro.
Molecular and Functional Characteristics of APJ
M. Hosoya,Y. Kawamata,S. Fukusumi,Ryo Fujii,Y. Habata,S. Hinuma,C. Kitada,S. Honda,T. Kurokawa,H. Onda,O. Nishimura,M. Fujino
Published 2000 in Journal of Biological Chemistry
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- Publication year
2000
- Venue
Journal of Biological Chemistry
- Publication date
2000-07-14
- Fields of study
Biology, Medicine, Chemistry
- Identifiers
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Semantic Scholar, PubMed
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