Figure 5.

Phylogenetic tree of olfactory receptor (OR) genes from the MHC-linked clusters in human and mouse and representatives from other human clusters. The most conserved block of 98 amino acids (including TM2 and TM3) was aligned in 99 ORs, analyzed by the maximum parsimony method and confirmed by 1000 bootstrap replicates (values shown only for most recent divergences). The alignment and all the OR sequences used here are available from our ftp site (see Methods for details). For the alignment of OR pseudogenes (suffixed P), a total of nine dashes were introduced where required to correct for frameshift mutations. The human β-3 adrenergic receptor (B3AR), accession no. P13945, was used as an outgroup.