Stefin B Antibody

Cystatin B (CSTB), also called Stefin B (STFB), is a small protein that is a member of the superfamily of cysteine protease inhibitors. It has been isolated from human spleen and liver and its amino acid sequence has been fully determined. The gene is located on 21q22.3. The protein is widely distributed and is localized mostly intracellularly, but has been found extracellularly. It is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. Its role is though to be as a protector against the proteinases leaking from lysosomes. A STFB multiprotein complex might have a specific cerebellar function, and that the loss of this function might contribute to the etiopathogenesis of EPM1. Upon differentiation to myotubes, STFB becomes excluded from the nucleus and lysosomes, suggesting that the subcellular distribution of the protein is dependent on the differentiation status of the cell.