Conserved olfactory receptor (OR) specific motifs used to identify OR genes in the pig genome, and the frequency of sequences with or without these motifs. (A) The amino acid sequences of the OR specific motifs are shown. The numbers indicate the positions of amino acids. TM, transmembrane domain. (B) Proportional distribution of the 1,301 functional and pseudo OR amino acid sequences identified by their OR motif containing patterns. The motifs within parentheses were absent. The absence or presence of the GN motif was not indicated.