Human cathepsin B (GenBank Accession No. NM_001908), CD33 signal peptide(amino acids 1-16) + Cathepsin B (amino acids 18-339), with C-terminal HIS tag, MW = 43 kDa, expressed in FreeStyle 293-F cells. Cathepsin B is a cysteine protease, found in the lysosome of normal cells and tissues. Cathepsin B active human is encoded by the gene CTSB, located on human chromosome 8p23.1.
Cathepsin B Active human primarily is a preproenzyme, glycosylated on rough endoplasmic reticulum. Processing of procathepsin B to a 31 kDa, single chain active form occurs in the lysosome. It is further processed to double chain form with a 25/26 kDa heavy chain and 5 kDa heavy chain in lysosome. Cathepsin B, functions as an exopeptidase at low pH. At higher pH in endosomes or neutral pH, cathepsin B functions as endopeptidase. Cathepsin B expression is upregulated in malignant tumors and facilitates tumor invasion. Cathepsin B might reduce the production of amyloid-β peptide associated with Alzheimerβs disease. It also plays a key role in neuroprotective functions.
