Cysteine cathepsins are known to primarily cleave their substrates at reducing and acidic conditions within endo-lysosomes. They have also been linked to extracellular proteolysis. We developed an assay to test for proteolytic processing of a natural substrate by cysteine cathepsins in the extracellular space. Our study emphasizes that the proteolytic functions of cysteine cathepsins in the thyroid are not restricted to endo-lysosomes but include pivotal roles in extracellular substrate utilization. We have approached this by simulating physiological conditions in protease activity assays.
COBISS.SI-ID: 233574779
Cathepsin B and other cysteine proteases are synthesized as zymogens, which are processed to their mature forms autocatalytically or by other proteases. Initiation of the autocatalytic processing has not yet been clarified. A model for autocatalytic activation of cysteine cathepsins is proposed, involving propeptide dissociation from the active-site cleft, followed by a bimolecular proteolytic removal of the propeptide. Such activation, may have important physiological consequences because cathepsin zymogens were often found secreted in various pathological states.
COBISS.SI-ID: 22392615