Purification of a squid nonmuscle myosin II.
Coomassie-stained 8.5% SDS-PAGE of optic lobe homogenate (H),
supernatants (S) and corresponding pellets (P) of squid optic lobe
samples obtained by a series of four centrifugation steps (S1-P4). The
final high-speed supernatant, S4 fraction, (indicated by asterisks) is
enriched in a high molecular weight protein (p220). The ∼220 kDa
protein (arrow) was further separated from other proteins by gel
filtration of the S4 fraction in the presence of ATP (GF68). Molecular
weight markers indicated by dashes on left: 200, 116, 98, 68, 31 kDa.