Tonight, the same old, deadly programme : BH3-only proteins, mitochondria and yeast

Apoptosis is a type of programmed cell death (PCD) conserved among metazoans and crucial for the development and homeostasis of tissues in multicellular organisms. Lower unicellular eukaryotes like yeast would thus have no need for it and they apparently lack the key regulators of mitochondria-dependent apoptosis. In this issue, Buttner et al (2011) challenge this view, discovering Ybh3p, a yeast protein homologous to the proapoptotic 'BH3-only' members of the mammalian Bcl-2 death regulators. Ybh3p kills yeast and mammalian cells impinging on inner mitochondrial membrane (IMM) proteins. Thus, mitochondria-dependent PCD emerges as an ancestral response of all eukaryotes, including unicellular ones.