Cathepsin A

[9] This gene encodes a glycoprotein that associates with lysosomal enzymes beta-galactosidase and neuraminidase to form a complex of high-molecular-weight multimers.

[10] CTSA is part of the Renin Angiotensin System (RAS).

Substrates of the enzyme that have been identified in vitro include endothelin I, angiotensin I, bradykinin, Substance P, and oxytocin.

Cathepsin A is one of 14 human enzymes commonly inhibited by organophosphate pesticides and phosphonate nerve agents.

Cathepsin A can be inhibited by sarin, soman, cyclosarin, VX, and VR.

Active site of Cathepsin A. In green is the Rebek pair. The two glutamate side chains are directed towards one another. To prevent an unfavorable charge-charge interaction the pKa of one glutamate side chain is raised to ~13.
Peptide substrates of Cathepsin A. CTSA is part of the Renin-Angiotensin System (RAS)