Mitofusin 2 Builds a Bridge between ER and Mitochondria

Mutations in mitofusin 2 (MFN2), a dynamin-like GTPase required for mitochondrial fusion, cause the peripheral neuropathy Charcot-Marie-Tooth type 2A. In a recent report in Nature, de Brito and Scorrano (2008) demonstrate a new function of MFN2-tethering the endoplasmic reticulum and mitochondria to control the efficiency of mitochondrial uptake of Ca(2+) ions.