cathepsin B

Cathepsins are a family of lysosomal proteases (serine, aspartic and cysteine proteases) that acts in conjunction with lipases and nucleases to degrade biological macromolecules in the lysosomes (1). While most cathepsins are ubiquitously expressed to support normal lysosomal degradation, cathepsin B is unique for its role in various pathologies and malignancies (2). Cathepsin B is often overexpressed and alternatively spliced in cancer cells (2).

Cell death via apoptosis is a key cellular function triggered by the cell death receptor family and their ligands. This regulated process then transmits downstream signals through adaptor molecules ending with the caspase cysteine proteases. Caspase 11 has a heterotetrameric structure consisting of two anti-parallel heterodimers. Upon activation, it is cleaved by an autocatalytic mechanism to give rise to individual subunits. This post-translational regulation enables rapid activation. Expression levels of caspase 11 are highest in lung and spleen.