Multiple sequence alignment of the OmcB proteins of C. trachomatis , C. pneumoniae and C. psittaci. The multiple sequence alignment was performed using the ClustalW program. The selected N-terminal and C-terminal regions, which represent a lesser degree of similarity, are boxed. Stars mark identical amino acid residues in all sequences in the alignment. Dashes represent gaps in the alignment introduced by the ClustalW program. Conserved amino acids are shaded dark grey and physico-chemical conserved amino acids are shaded in light grey.