Along with Mitofusin-2 (Mfn2), Mitofusin-1 (Mfn1) is a known protein mediator of mitochondrial fusion. Mitochondrial fusion regulates mitochondrial morphogensis and supports complementation between mitochondrial genomes in mammalian cells. Two Mfn1 transcripts are detected at similar levels in a variety of human tissues and are dramatically elevated in the heart. Human Mfn1 is known to be localized in the mitochondria. It is reported that point mutations in the conserved G1 and G2 region of the Mfn1 GTPase domain result in decreased formation and fragmentation of the mitochondria, respectively.