The protein encoded by this gene is a mediator of mitochondrial fusion. This protein and mitofusin 2 are homologs of the Drosophila protein fuzzy onion (Fzo). They are mitochondrial membrane proteins that interact with each other to facilitate mitochondrial targeting. [provided by RefSeq, Jul 2008],catalytic activity:GTP + H(2)O = GDP + phosphate.,function:Essential transmembrane GTPase, which mediates mitochondrial fusion. Fusion of mitochondria occurs in many cell types and constitutes an important step in mitochondria morphology, which is balanced between fusion and fission. MFN1 acts independently of the cytoskeleton. Overexpression induces the formation of mitochondrial networks.,similarity:Belongs to the mitofusin family.,subunit:Forms homomultimers and heteromultimers with MFN2. Multimerization, which is probably mediated by the coiled coil region, may play an essential role in mitochondrion fusion (By similarity). Participates in a high molecular weight multiprotein complex.,tissue specificity:Ubiquitous. Expressed at slightly higher level in kidney and heart. Isoform 2 may be overexpressed in some tumors, such as lung cancers.,