Figure 1. Protein sequence alignments of mature regions of known human cathepsins, other rodent cathepsins and related proteins, and plant papain and aleurain. Although only human and selected sequences are shown, the original dataset used for generating the alignments contained 43 vertebrate and two plant sequences, identified by a BLAST search of the GenBank non-redundant database (Altschul et al., 1990). The sequence abbreviations and GenBank entries for the sequences shown are: hDPP I, human dipeptidyl peptidase I, P53634; hB, human cathepsin B, NP_001899; hV, human cathepsin V, AAC23593; hL, human cathepsin L, NP_001903; rtestin, rat testin, P15242; mP, mouse cathepsin P, NP_036137; rCLRP, rat cathepsin L-related protein, I58002; rQ, rat cathepsin Q, AAF01247; mM, mouse cathepsin M, AAF68224; hK, human cathepsin K, P43235; hS, human cathepsin S, P25774; hH, human cathepsin H, P09668; Aleurain, plant, P05167; Papain, plant, P00784; hF, human cathepsin F, NP_003784; hX, human cathepsin X, NP_001327; hLym, human lymphopain, P56202; and hO, human cathepsin O, NP_00135. Propeptide cleavage sites were obtained from the GenBank entries, or from preliminary alignments. Alignments of the predicted mature proteins were generated based on the default settings of ClustalX (Thompson et al., 1997). Introduced gaps are shown as "-". The alignment is in good agreement with that of other published ones, including those based on structure. To derive consensus sequences, we processed alignment files using the public domain software BOXSHADE (written by K. Hofmann and M. Baron, www.ch.embnet.org/software/BOX_form.html). Predominant identical residues (> 50%) at a position are shown with a black background, predominant similar residues on a grey background. The majority consensus residue is shown under each alignment. An uppercase letter shows a residue conserved in all aligned sequences. An * under the consensus sequence denotes the active-site cysteine and histidine residues conserved in all functional peptidases.