Cathepsin D

Cathepsin D is a is_associated_with::protein that in humans is encoded by the CTSD is_associated_with::gene.

It has been used as a is_associated_with::breast cancer is_associated_with::tumor marker.

Cathepsin-D is an aspartic protease that depends critically on protonation of its active site Asp residue and gets activated at pH 5 in is_associated_with::endosome of is_associated_with::hepatocytes where it degrades is_associated_with::insulin. Along with Asp-protonation, lower pH also leads to conformational switch in cathepsin-D : the N terminal segment of the protease moves out of the active site as pH drops. is_associated_with::Ceramide binds-to and activates cathepsin D.