PMC

Phylogenic distribution of caspases, metacaspases, paracaspases, and bacterial para-/metacaspase-like proteins. C, caspase; MC, metacaspase; PC, paracaspase; protoPC/MC, bacterial para-/metacaspase-like proteins. Classification of cellular life into one prokaryotic (Bacteria, including Archaebacteria) and five eukaryotic kingdoms (Fungi, Protozoa, Chromista, Animalia, and Plantae) as described in . HGT events are indicated by dotted arrows.

Structural properties of caspases, paracaspases, and metacaspases. (A) Schematic representation of the domains of caspases (C), metacaspases (MC), and paracaspases (PC). The catalytic domains consist of a large p20 (red) and small p10 subunit (green). Positions of the catalytic His and Cys residues are indicated by yellow bars. Prodomains of inflammatory and proapoptotic initiator caspases and type I metacaspases are in gray. The N-terminal domain of paracaspases contains a death domain (black) and one or two Ig domains (blue). The C-terminal region of paracaspases, which is involved in ubiquitination, is shown in pink. (B) Topological diagram of the structure of human caspase 8 and metacaspase 9 of Arabidopsis thaliana. Catalytic His and Cys residues are labeled in red, (putative) S1 pocket–forming residues are in blue, and maturation sites are in green. Figure layout is adapted from the diagram for human caspase 8 in . The secondary structure of AtMC9 was predicted using the Protein Structure Prediction Server ().