Figure 1.

The primary mitochondrial dynamics machinery responsible for mitochondrial membrane fusion and fission. Outer mitochondrial membrane fusion is primarily mediated by mitofusin 1 and 2 (Mfn1 and Mfn2). (A–C) Homotypic Mfn1 and Mfn2 complexes or heterotypic Mfn1:Mfn2 complexes execute outer membrane fusion. (D) Optic atrophy 1 (Opa1) is the large guanosine triphosphate hydrolase (GTPase) that mediates inner mitochondrial membrane fusion. Inner mitochondrial membrane fusion is typically coupled with outer mitochondrial membrane fusion. (E) Dynamin-related protein 1 (Drp1) oligomerizes as spirals around the mitochondrial membrane. Upon GTP hydrolysis, the mitochondria are greatly constricted which serves as the platform for Dynamin-2 (Dyn2) to complete fission of the mitochondrial unit.