Nucleotide and deduced amino acid sequence of Ixodes ricinus cathepsin B, form 1 (IrCB). The PCR primers used are upperlined and named as in Table 1 and 2. The predicted 17 AA signal peptide is underlined, in italics. Three potential N-glycosylation sites are double underlined and the respective asparagine residues are in bold; Active site residues C113, H282, Q107and N302 are bold and shaded. Occluding loop responsible for cathepsin B exo-peptidase activity is bold, and italics.