Figure 1.

Model for mitochondrial fusion/fission in mammalian cells. Mitochondria can undergo constriction and division (1). These events are mediated by the cytosolic Drp1, which bonds and localizes to the constriction site via an interaction with the receptor (anchor)-like protein human Fis1 (hFis1) (2). During fusion, a tether of the MFN-1 or -2 to collateral mitochondrial MFN-1 and -2 conjoins the outer membranes. OPA1, an inner membrane GTPase protein facilitates the fusion of the inner membrane, cristae formation, and unifying of compartments.