Fig. 1

Odorant-binding proteins (OBP) in anal sac gland secretions of dogs. A Picture of dog behaviour that shows the investigation of anal zones. B Canine anal sacs are situated at both sides of the anus. C Sequence alignment of OBP isoforms of canine ASGS. The signal peptide and the functional protein are marked in grey and black, respectively. Stars show identical amino acids in all proteins. Signature residues and motifs that are conserved among most mammalian lipocalins are included below the amino acid sequences. D Obp gene organisation in the dog genome. The obp gene cluster is situated on the X chromosome and obtains three genes with nucleotide positions of obp1: 2,893,438–2,899,738, obp2: 2,905,438–2,911,062, and obp3: 2,918,198–2,923,699. E Obp gene structure: every dog obp gene contains seven exons of which exons 1 to 6 span the coding region. UTR = untranslated regions at the 5ʹ and 3ʹ ends; SP = signal peptide