FOCAL POINT Two groups of researchers implicate different mitochondrial proteases in the regulation of OPA1, a dynamin-related GTPase that promotes mitochondrial inner membrane fusion. Ehses et al., led by Thomas Langer (top left), find that the m-AAA protease maintains the correct balance of long and short OPA1 isoforms—the mitochondrial network is fragmented in the absence of two of the protease's subunits (bottom row). Both groups reveal that a second protease, OMA1, completely cleaves long versions of OPA1 to prevent damaged mitochondria from fusing. Brian Head (top right), Lorena Griparic (center left), Alexander van der Bliek (center right), and colleagues find that OMA1 itself is also regulated by proteolysis.