Fig. 4: Model for Drp1 regulation.

a Two dimers from the crystal structure (PDB ID: 4BEJ) are aligned to the dynamin interface 1. b Two dimers of the dimeric cryoEM structure are aligned to the dynamin interface 1. c Top down view of the dimeric cryoEM structure aligned to the dynamin interface 1. Chains not involved in the interface are in gray. Inset box provided for reference, crystal structure interface 1 top, dimeric cryoEM structure interface 1 bottom. d Steric clashes between adjacent chains in the cryoEM structure would prevent proper interface alignment of interface 1. e Top-down view of the dimeric cryoEM structure aligned to the dynamin interface 3. Chains not involved in the interface are in gray. Inset box provided for reference, crystal structure interface 3 top, dimeric cryoEM structure interface 3 bottom. f Steric clashes between adjacent chains in the cryoEM structure would prevent proper interface alignment of interface 3. g The dimeric cryo-EM structure (bottom left) is in an autoinhibited state. The BSE lock and the closed dimer interface are maintained by weak intramolecular interactions. Intermolecular interactions between Drp1 and partner proteins, organelle contact sites, and/or lipid interactions relieve inhibition to promote an assembly-primed conformation. Helical assembly requires both an open dimer interface and an unlocked, extended G Domain. GTPase domain in green, stalk in dark blue, GED in light blue, BSE in red (N-terminal), and Pink (C-terminal). Variable domain not shown.