Fig. 1

a Multiple alignment of the amino acid sequence of corticotropin-releasing hormone (CRH) and CRH-related peptides. The rat Ucn1 has 45% similarity to rCRH, Ucn2 has 34% similarity to CRH, Ucn3 has 26% similarity to CRH, frog Sauvagine has 50% similarity to CRH, fish Urotensin has 50% similarity to CRH. b Multiple alignment of the amino acid sequence of urocortin precursors from different species including some domestic animals. Rat mature Ucn1 has 99–100% similarity to dog, cow, horse, sheep, pig, alpaca, buffalo, and goat Ucn1. Ucn1 sequences have 99–100% similarity among different domestic animal species. Sequences were aligned using Clustal W then highlighted using BoxShade 3.21, which shades conserved residues according to whether they are completely conserved (black) or similar (gray). Hyphens indicate gaps in the sequence among the species. Asterisk indicates “predicted sequences”. c Binding affinity of CRHR-ligands. CRHR1 binds CRH as well as Ucn1, but not Ucn2 and Ucn3, whereas CRHR2 binds Ucns with a higher binding affinity than CRH. A proline residue at position 11 (bold letter) is found only in CRHR2-selective ligands, Ucn2 and Ucn3. These peptides also contain alanine residues at positions 35 and 39 (bold letters)