Abstract
In spite of importance of programmed cell death, few orthologs of animal apoptosis regulators have been found in plants. We have identified two novel genes encoding proteins homologous to mammalian inhibitor of apoptosis protein (IAP), Arabidopsis thaliana IAP-like protein (AtILP) 1 and 2 in the Arabidopsis genome. ILP genes also existed in other organisms including budding yeast, nematode and vertebrates and constitute a novel gene family. Like baculovirus IAP repeats (BIR) in IAPs, ILP proteins contain two (usually one complete and one separated) highly conserved BIR-like domains (BLDs). BLDs, like BIRs, have a putative C2HC-type zinc finger, a derivative of C2H2-type zinc finger. Phylogenetic analyses based on C2H2-type zinc finger motifs indicated that ILPs are putative paralogs of IAPs. These findings suggest the conservation of ILPs in wide-range of eukaryotes, including plants, and their closely related functions to IAPs.
