Fig. 6: Proposed mechanism of AtMC9 activation and regulation.
From: Structural determinants for pH-dependent activation of a plant metacaspase
Surface model of the structures surrounding the active site region of AtMC9, with the key modulating residues outlined and labeled. Blue down-arrows signify decreased activation. The red up-arrow indicates increased activation. Black spindles represent suppressive functions as Glu112 keeps Cys147 away from cleaving the inhibitory Arg183 in the active site at a neutral pH or higher. In contrast, the Black arrow indicates the activating function of Glu255 and His307, as these residues may push Cys147 toward Arg183 under acidic pH conditions.
