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General Comment |
Cathepsins are papain family cysteine proteases that represent a major component of the lysosomal proteolytic system. They
are synthesized as inactive precursors consisting of a signal sequence, a propeptide, and a catalytically active mature region.
Cathepsins are routed to the endosomal/lysosomal compartment via the mannose 6-phosphate receptor pathway.
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 by Nagler DK et al . 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.
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