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. Author manuscript; available in PMC: 2009 Jan 1.
Published in final edited form as: Nat Struct Mol Biol. 2008 Jul;15(7):658–664. doi: 10.1038/nsmb.1451

Figure 2.

Figure 2

Mitochondrial fusion and cell fusion in mating yeast cells. (a) Mitochondria initiate contact and fusion through the interaction of Fzo1 (or Mfn in mammals), a dynamin-like GTPase located in the outer mitochondrial membrane. The fusion of the outer membrane occurs first, and then inner membrane contact and fusion is regulated by another dynamin-like GTPase, Mgm1 (or OPA1 in mammals). Ugo1 in the outer membrane provides a physical link between Fzo1 and Mgm1. (b) Yeast cells initiate cell fusion by regulated expression of two membrane proteins, Fus1p (a single-pass membrane protein) and Prm1p (a multispanning membrane protein), and a cytoplasmic protein, Fus2p. Fus1p and Fus2p localize to the cell mating tip and are required for the dissolution of the cell wall separating the plasma membranes of the mating pair. Prm1p is required for some as-yet-undefined reaction, possibly the formation of a fusion pore, that occurs when the mating cell plasma membranes come into contact.