Figure 2.

Processing and localization of phytaspase in healthy and dying plant cells, as compared with the behaviour of caspases in animal cells. Death proteases in animals (caspases) and in plants (phytaspases) are synthesized as inactive precursor proteins. Caspase precursors are stored within healthy animal cells until an apoptogenic stimulus triggers their processing/activation.⁵⁰ In contrast to this scenario, phytaspase precursors are constitutively processed and the resultant mature enzymes secreted from healthy plant cells. Upon programmed cell death (PCD) induction, phytaspase is imported into plant cells through an undefined mechanism⁴⁹