33-kDa peptides prepared from chicken gizzard smooth muscle bundle both actin and desmin filaments in vitro

A group of 33-kDa peptides was prepared from chicken gizzard. Gizzard smooth muscle was extracted with Hasselbach-Schneider's high ionic strength solution. The extract was fractionated by ammonium sulfate precipitation. The soluble fraction obtained at 60% ammonium sulfate saturation was dialyzed against 0.1 M KCl. The precipitate formed during the dialysis mainly contained 33-kDa peptides. On SDS-PAGE, two major bands and one minor band were stained reddish purple by Coomassie Brilliant Blue R-250. These peptides, which were insoluble in physiological salt solutions, bundled not only actin filaments but also desmin filaments. Actin was markedly coprecipitated with the 33-kDa peptides on the usual centrifugation at 22,000 x g.