Effector protein that binds to the host serine protease cathepsin G on the macrophage cell membrane, inhibiting its enzymatic activity and the downstream activation of caspase-1-dependent apoptosis. Thus prevents macrophage pyroptosis and helps M.tuberculosis survival within host cells. Interacts with human cathepsin G protein. Is translocated into the cytoplasm of macrophages. Component of the signal transduction operon Rv3361c-Rv3365c that is highly up-regulated during M.tuberculosis infection of macrophages. Belongs to the mycobacterial serine protease inhibitor Rv3364c family.