Has a role in mitochondrial fission. Has a role in outer membrane fission but not matrix separation (By similarity). Highly expressed during fruit body ripening. Levels increase during fruit body stages 1, 2 and 3, the stages of ascospore formation and maturation. Levels decrease during mycelium aging. The C-terminus is required for mitochondrial localization, while the N-terminus is necessary for mitochondrial fission. Belongs to the FIS1 family.