Mapping the ATL2 C-terminal inhibitory domain. (A) Schematic of serial truncations of the ATL2 C-terminal extension. C-terminal residues identical in D. rerio ATL2 are in bold. Initial fusion rates were calculated from the data shown in B. AH, amphipathic helix. (B) Lipid mixing by the ATL2 truncations shown in A. (C) Schematic of serial truncations of the ATL1 C-terminal extension. C-terminal residues identical in D. rerio ATL1 in bold. Fusion rates were calculated from the data shown in D. (D) Lipid mixing by the ATL1 truncations shown in C. All proteins were incorporated at a 1:1,000 protein/lipid ratio, and the data are the average of at least two independent traces.