title: Human cathepsin X: a novel cysteine protease of the papain family with a very short proregion and unique insertions.
abstract: A novel cDNA encoding a cysteine protease of the papain family named cathepsin X was obtained by PCR amplification from a human ovary cDNA library. The cathepsin X cDNA is ubiquitously expressed in human tissues and contains an open reading frame of 912 nucleotides encoding a predicted protein of 303 amino acids. All highly conserved regions in papain-like cysteine proteases including the catalytic residues are present in cathepsin X. The mature part of cathepsin X is 26-32% identical to human cathepsins B, C, H, K, L, O, S and W. The cathepsin X sequence contains several unique features: (i) a very short proregion; (ii) a three amino acid residue insertion in a highly conserved region between the glutamine of the putative oxyanion hole and the active site cysteine; and (iii) a second insertion of 15 amino acid residues that can be aligned with the occluding loop region in cathepsin B.
authors.affiliation: Biotechnology Research Institute, National Research Council of Canada, Montréal, Qué.
authors.forename: D K
authors.initials: DK
authors.lastname: Nägler
authors.forename: R
authors.initials: R
authors.lastname: Ménard
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D056657:Cathepsin K; D002403:Cathepsins / Q000235:genetics* / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D004251:DNA Transposable Elements; D006801:Humans; D008969:Molecular Sequence Data; D010206:Papain / Q000235:genetics*; D016415:Sequence Alignment; D017421:Sequence Analysis
chemical_list: D004251:DNA Transposable Elements; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D010206:Papain; C534130:CTSK protein, human; D056657:Cathepsin K