BAX Inhibitor-1, an ancient cell death suppressor in animals and plants with prokaryotic relatives.
BAX Inhibitor-1 (BI-1) was originally described as testis enhanced gene transcript in mammals. Functional screening in yeast for human proteins that can inhibit the cell death provoking function of BAX, a proapoptotic Bcl-2 family member, led to functional characterisation and renaming of BI-1. The identification of functional homologues of BI-1 in plants and yeast widened the understanding of BI-1 function as an ancient suppressor of programmed cell death. BI-1 is one of the few cell death suppressors conserved in animals and plants. Computer predictions and experimental data together suggest that BI-1 is a membrane spanning protein with 6 to 7 transmembrane domains and a cytoplasmic C-terminus sticking in the endoplasmatic reticulum and nuclear envelope. Proteins similar to BI-1 are present in other eukaryotes, bacteria, and even viruses encode BI-1 like proteins. BI-1 is involved in development, response to biotic and abiotic stress and probably represents an indispensable cell protectant. BI-1 appears to suppress cell death induced by mitochondrial dysfunction, reactive oxygen species or elevated cytosolic Ca(2+) levels. This review focuses on the present understanding about BI-1 and suggests potential directions for further analyses of this increasingly noticed protein.
Hückelhoven
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Institute of Phytopathology and Applied Zoology, Justus-Liebig-University Giessen, Heinrich-Buff Ring 26-32, D-35392 Giessen, Germany. Ralph.Hueckelhoven@agrar.uni-giessen.de
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D003593:Cytoplasm / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry; D006801:Humans; D007113:Immunity, Innate; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000737:chemistry; D010802:Phylogeny; D010944:Plants; D011387:Prokaryotic Cells / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D009626:Terminology as Topic; D014018:Tissue Distribution; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D008565:Membrane Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein