Developmentally regulated mitochondrial fusion mediated by a conserved, novel, predicted GTPase

Cell. 1997 Jul 11;90(1):121-9. doi: 10.1016/s0092-8674(00)80319-0.


The Drosophila melanogaster fuzzy onions (fzo) gene encodes the first known protein mediator of mitochondrial fusion. During Drosophila spermatogenesis, mitochondria in early postmeiotic spermatids aggregate, fuse, and elongate beside the growing flagellar axoneme. fzo mutant males are defective in this developmentally regulated mitochondrial fusion and are sterile. fzo encodes a large, novel, predicted transmembrane GTPase that becomes detectable on spermatid mitochondria late in meiosis II, just prior to fusion, and disappears soon after fusion is complete. Missense mutations that alter conserved residues required for GTP binding in other GTPases inhibit the fusogenic activity of Fzo in vivo but do not affect its localization. Fzo has homologs of unknown function in mammals, nematodes, and yeast.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Chromosome Mapping
  • Conserved Sequence
  • Drosophila Proteins*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / physiology*
  • Female
  • GTP Phosphohydrolases / chemistry
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • Genes, Insect
  • Genes, Recessive
  • Humans
  • Infertility, Male / genetics
  • Intracellular Membranes / physiology
  • Male
  • Membrane Fusion*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mitochondria / physiology*
  • Mitochondria / ultrastructure
  • Molecular Sequence Data
  • Mutagenesis
  • Polymorphism, Genetic
  • Recombination, Genetic
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Spermatids / physiology


  • Drosophila Proteins
  • Membrane Proteins
  • Fzo protein, Drosophila
  • GTP Phosphohydrolases

Associated data

  • GENBANK/U95821