Mitochondrial fission is primarily mediated by the protein Drp1 (Dynamin-related protein 1), which constricts the mitochondrial membrane to divide it into two. On the other hand, mitochondrial fusion is facilitated by the proteins Mfn1, Mfn2 (Mitofusins 1 and 2), and OPA1 (Optic Atrophy 1), which help merge the outer and inner mitochondrial membranes, respectively.
