Fig. 1.

Fig. 1. Mitochondrial targeting domain (MTD) homologs induce necrotic cell death as in MTD. A. (Left panel) There are several mitochondrial targeting domain (MTD) homologs in human genes. They were searched by protein basic local alignment search tool (BLAST) on National Center for Biotechnology Information (NCBI) and sorted according to percent identity with MTD. Each amino acid was colored according to the ClustalX color scheme (hydrophobic, blue; positive charge, red; negative charge, magenta; polar, green; glycine, orange; proline, yellow; aromatic, cyan; cysteine, pink). (Right panel) The cytotoxicity of mitochondrial targeting domain (MTD) homologs is determined by its amino acid sequence. MTD homologs were grouped according to their cytotoxicity, then sorted according to percent identity with MTD. Each amino acid was colored according to the ClustalX color scheme (hydrophobic, blue; positive charge, red; negative charge, magenta; polar, green; glycine, orange; proline, yellow; aromatic, cyan; cysteine, pink). B. Cell viabilities were determined by MTS assay 1 h after treating HeLa cells with MTD homologs fused with octa-arginine (R8). HeLa cells treated with R8:M-LIPRIN, R8:MST3GAL3, R8:M-TRRAD, and R8:M-SDAD1(left panel). HeLa cells treated with eM-GAL3, R8:MGAL3, and R8:M-ST13 (right panel). C, HeLa cells treated with R8:M-SDAD1 (5 μM), R8:M-TRRAD (20 μM), and R8:M-ST3GAL3 (40 μM), then observed for 10 min using differential interference contrast microscopy. D, HeLa cells were treated with R8:M-SDAD1 (10 μM), R8:M-TRRAD (20 μM), and R8:M-ST3GAL3 (40 μM), with and without DIDS (200 μM); after 1 h, cell viability was determined by MTS assay.

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