Amphibian bombesin is the prototypic peptide that defines the bombesin-like peptide family. In this paper we show that in the frog Bombina orientalis, there are actually 3 distinct forms of bombesin, and each of these peptides is an agonist with differing affinities for the known bombesin receptors. Oligonucleotides complementary to the 5`- and 3`-untranslated regions of the bombesin mRNA were used to amplify bombesin-related cDNAs from the skin, brain, and gut of B. orientalis. Three classes of cDNAs were found. One class encoded the previously characterized form of bombesin which has a Leu at position 13 ([Leu]bombesin). The other two classes, respectively, encoded new bombesin-like peptides which we have designated as [Phe]bombesin and [Ser,Arg,Phe]bombesin ([SAP]bombesin). The existence of [SAP]bombesin in skin was confirmed by tandem mass spectrometry. Polymerase chain reaction analysis of genomic DNA showed the mRNAs for [Leu]bombesin, [Phe]bombesin, and [SAP]bombesin most likely arise from separate genes. Polymerase chain reaction analysis showed different patterns of tissue-specific expression for each form. [Leu]Bombesin and [SAP]bombesin were predominantly expressed in skin, brain, and gut; [Phe]bombesin was expressed only in brain, and [Leu]bombesin predominated in oocytes. [SAP]Bombesin contained a cleavage site between residues 4 and 5, which if used would yield the peptide [SAP]bombesin(5-14) which has the sequence [Gln,Arg]neuromedin B. Thus a frog homolog of NMB could derive from the [SAP]bombesin prohormone. [Phe]Bombesin, [SAP]bombesin, and [SAP]bombesin(5-14) were synthesized and their affinities for the mammalian bombesin-like peptide (GRP and NMB) receptors determined. These peptides acted as agonists for the GRP and NMB receptors, with relative potencies for the GRP receptor of [Leu]bombesin > [Phe]bombesin > [SAP]bombesin(5-14) > [SAP]bombesin and for the NMB receptor of [Phe]bombesin > [SAP]bombesin(5-14) > [Leu]bombesin > [SAP]bombesin. None of these peptides demonstrated high affinity binding for the BRS-3 receptor. The different receptor affinities and tissue distribution of these peptides suggests distinct physiologic roles and raises the possibility of as yet uncharacterized mammalian homologs of these new amphibian peptides.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				R. T. Jensen, J. F. Battey, E. R. Spindel, and R. V. Benya International Union of Pharmacology. LXVIII. Mammalian Bombesin Receptors: Nomenclature, Distribution, Pharmacology, Signaling, and Functions in Normal and Disease States Pharmacol. Rev., March 1, 2008; 60(1): 1 - 42. [Abstract] [Full Text] [PDF]

				S. L. DeBlasio, D. L. Luesse, and R. P. Hangarter A Plant-Specific Protein Essential for Blue-Light-Induced Chloroplast Movements Plant Physiology, September 1, 2005; 139(1): 101 - 114. [Abstract] [Full Text] [PDF]

				B. J. Proskocil, H. S. Sekhon, Y. Jia, V. Savchenko, R. D. Blakely, J. Lindstrom, and E. R. Spindel Acetylcholine Is an Autocrine or Paracrine Hormone Synthesized and Secreted by Airway Bronchial Epithelial Cells Endocrinology, May 1, 2004; 145(5): 2498 - 2506. [Abstract] [Full Text] [PDF]

				P. Pattee, A.-E. Ilie, S. Benyhe, G. Toth, A. Borsodi, and S. R. Nagalla Cloning and Characterization of Xen-dorphin Prohormone from Xenopus laevis: A NEW OPIOID-LIKE PROHORMONE DISTINCT FROM PROENKEPHALIN AND PRODYNORPHIN J. Biol. Chem., December 26, 2003; 278(52): 53098 - 53104. [Abstract] [Full Text] [PDF]

				B. Y. Williams, S. B. Dion, and A. Schonbrunn Role of Receptor and Protein Kinase C Activation in the Internalization of the Gastrin-Releasing Peptide Receptor Mol. Pharmacol., November 1, 1998; 54(5): 889 - 898. [Abstract] [Full Text]

				R. R. Ryan, H. C. Weber, W. Hou, E. Sainz, S. A. Mantey, J. F. Battey, D. H. Coy, and R. T. Jensen Ability of Various Bombesin Receptor Agonists and Antagonists to Alter Intracellular Signaling of the Human Orphan Receptor BRS-3 J. Biol. Chem., May 29, 1998; 273(22): 13613 - 13624. [Abstract] [Full Text] [PDF]

				H.-S. Kim, S. R. Nagalla, Y. Oh, E. Wilson, C. T. Roberts Jr., and R. G. Rosenfeld Identification of a family of low-affinity insulin-like growth factor binding proteins (IGFBPs): Characterization of connective tissue growth factor as a member of the IGFBP superfamily PNAS, November 25, 1997; 94(24): 12981 - 12986. [Abstract] [Full Text] [PDF]