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Fig. 1 The T248I mutation in vps4a reduces ATPase activity and ESCRT-III filament disassembly. A, vps4a is located on Chromosome 25 in a location corresponding to where classical mapping methods have identified the location of the gene responsible for the raumschiff phenotypes. B, Bar diagram of Vps4a protein showing the location of the T248I mutation. C, Atomic model structure of the Vps4E233Q hexamer, with T248 marked in magenta (Image adapted from the RCSB PDB ID:5XMI, using Mol*). D, Mutant Vps4 (T254I) yeast protein has decreased ATP activity compared with wild-type Vps4 protein. Unpaired t test; p < 0.0001; nWT = 4; nvps4(T254I) = 4; t = 47.92; df = 6. E, Sedimentation analysis of Vps4 and Vps4(T254I)-mediated disassembly of ESCRT-III filaments. Pellet (P) and supernatant (S) fractions were analyzed by SDS?PAGE. Marker (M). F, Negative staining EM micrograph of sedimentation analysis of ESCRT-III filament disassembly.