Figure 1

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Figure 1. Domain architectures of apoptotic proteins and their advent in evolution. The evolutionary tree for the major divisions of life is shown under the assumptions of an archaeal-eukaryotic clade (28) and a coelomate clade (see text). Each box shows the domain architectures of proteins that are either specific to a particular lineage (for example, vertebrates) or are shared by the two lineages coming out of a given internal node (for example, vertebrates and arthropods) and therefore inferred to have been present in their common ancestor. The direction of probable horizontal transfer of genes encoding homologs of apoptotic proteins is tentatively shown by an arrow pointing from bacteria to eukaryotes. E.B., early branching (eukaryotes). Domain name abbreviations: De, Death effector domain; D, Death domain; C, Card domain; P, pyrin domain; Ig, immunoglobulin domain; Tig, transcription factor immunoglobulin domain (as in NFB); P53F, P53 fold all--strand domain; a20, A20-like Zn-finger; OTA20, OTU-A20-like predicted protease domain; S, SAM domain; R, RING finger; Cr, cysteine-rich domain; Math, meprin-associated Traf homology domain; Tir, Toll-interleukin 1 (IL1) receptor domain; ank, ankyrin repeat domain; TSP, thrombospondin domain; wd, WD40 propeller domain; zu5, zona pellucida Unc-5 domain; P84, conserved domain in the human P84 protein; c4, C4 "little" finger domain; CAD, common domain found in CAD and ICAD; UB, ubiquitin domain; UBC-E2, ubiquitin-conjugating E2 enzyme; tnfr, cysteine-rich domain in TNFR; Spry, SplA-ryanodine receptor domain; B, B-box domain; lrr, leucine-rich domain; arm, armadillo repeat; tpr, tetratricopeptide repeat; lsd1, plant hypersensitive response protein LSD1-like Zn-finger domain.