Atlastins. (A) All atlastins share a common domain structure. Mammalian paralogs ATL1, ATL2, and ATL3 have a highly conserved core consisting of the G domain, 3HB, TM hairpin, and AH. The paralogs differ in the HVR and CTE, the latter being alternatively spliced in ATL1 and 2. The HVR phosphorylation sites are shown. (B) Structural model of ATL. (C) Pre- and post-fusion structures of soluble ATL1. Formation of the post-fusion structure requires a 3HB conformational shift. The post-fusion structure is shown with its dimerization partner.