Mitofusin, involved in mitochondrial outer membrane fusion; mediates contacts between mitochondria and peroxisomes that regulate mitochondrial fusion; GTPase domain is required for auto-oligomerization and for efficient tethering, homotypic fusion and degradation of Fzo1p; role in mitochondrial genome maintenance; targeted for destruction by SCF-Mdm30p and the cytosolic ubiquitin-proteasome system; activity regulated by ubiquitination at conserved lysines and by deubiquitinases Ubp2p and Ubp12p