title: Differential responsiveness of CRF receptor subtypes to N-terminal truncation of peptidic ligands.
abstract: The role of the N-terminal domains of corticotropin-releasing factor (CRF) and CRF-like peptides in receptor subtype selectivity, ligand affinity and biological potency was investigated. Therefore, human CRF(12-41), human URP(12-38) and antisauvagine-30 (aSvg) were N-terminally prolonged by consecutive addition of one or two amino acids. The peptides obtained were tested for their binding affinities to rat CRF1 and murine CRF(2beta) receptor, and their capability to stimulate cAMP-release by HEK cells producing either receptor. It was observed that human CRF N-terminally truncated by eight residues was bound with high affinity to CRF2 receptor (Ki=5.4nM), whereas affinity for CRF1 receptor was decreased (Ki=250 nM). A similar shift of affinity was found with sauvagine (Svg) analogs. Truncation of human URP analogs did not affect their preference for CRF(2beta) receptor, but reduced their affinity. Changes in affinity were positively correlated with changes in potency. These results indicated that CRF1 receptor was more stringent in its structural requirements for ligands to exhibit high affinity binding than CRF(2beta) receptor.
authors.affiliation: Department of Molecular Neuroendocrinology, Max Planck Institute for Experimental Medicine, Hermann Rein Street 3, Goettingen, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Brauns
authors.forename: Simone
authors.initials: S
authors.lastname: Brauns
authors.forename: Bodo
authors.initials: B
authors.lastname: Zimmermann
authors.forename: Olaf
authors.initials: O
authors.lastname: Jahn
authors.forename: Joachim
authors.initials: J
authors.lastname: Spiess
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D018019:Receptors, Corticotropin-Releasing Hormone / Q000145:classification* / Q000378:metabolism*; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D054832:Urocortins
chemical_list: D008024:Ligands; D010446:Peptide Fragments; D018019:Receptors, Corticotropin-Releasing Hormone; D054832:Urocortins; C116607:antisauvagine 30; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP