Mitochondrial outer membrane fission factor involved in mitophagy; mitofissin-like microprotein that exhibits lipid membrane-binding and -fission activity, preferentially on cardiolipin-containing membranes; facilitates mitophagy independent of dynamin-like protein Dnm1p but requires mitochondrial intermembrane space mitofissin Atg44p; GFP-fusion protein localizes to the cytoplasm; low but significant homology with Atg44p and N-terminal structural similarity with full length Atg44p