Mitochondria (red) are stickier in cells that make faulty MARCH5 (green).
Cells carefully control mitochondrial fusion and fission, and an imbalance between the processes can be disastrous. For example, a faulty fusion-promoting protein triggers dominant optic atrophy, the leading cause of inherited blindness. Researchers know more about the regulation of fusion and fission in yeast than in mammals. But they do know that one of the mammalian proteins essential for mitochondrial breakup is Drp1.
Karbowski et al. pinpointed another, called MARCH5, which colocalizes with Drp1. Although two studies published last year suggested that MARCH5 promoted mitochondrial fusion, the scientists now find the opposite. When they altered cells to produce a defective version...
