Purification of high-salt–extractable actin assembly activity via biochemical reconstitution. (a) Purified membranes were incubated in high salt to obtain a stripped membrane fraction and a high-salt fraction. (b) Stripped membranes cannot assemble actin. (c) Dialyzed high-salt (HS) extract rescued actin assembly on stripped membranes. (b and c) Bars, 10 µm. (d) The actin assembly activity from high-salt extract binds to Q HP and source Q columns and subsequently purified on Superdex 200. Bars on traces show fractions with activity. (e) Purification table for actin assembly activity. AU, arbitrary unit. (f) Coomassie blue–stained gel for the purification of actin assembly activity. Lane 1, homogenate; lane 2, purified membrane; lane 3, high-salt stripped membrane; lane 4, high-salt extract; lane 5, S and Blue flowthrough; lane 6, heparin flowthrough; lane 7, Q HP fractions with peak activity; lane 8, source Q fractions with peak activity; lane 9, Superdex 200 fraction B13 with peak activity. Q PE, quaternary ammonium polystyrene/divinylbenzene; SHP, sulfopropyl high performance.