Isomin in vitro reassembly. (a) Negative staining of in vitro-reassembled isomin filament. Bar = 200 nm. The inset shows at a greater magnification two loosely packed filaments, revealing thinner protofilaments (arrowheads); bar = 100 nm. (b) Electrophoretic analysis on a 12% SDS-polyacrylamide gel of the sedimented (P) and supernatant (S) fraction after centrifugation of in-vitro reassembled isomin filaments. Migration of molecular weight reference proteins is indicated on the right.