Interaction of myosin subfragment-1 with actin. II. Location of the actin binding site in a fragment of subfragment-1 heavy chain.
The heavy chain of subfragment-1 prepared by chymotrypsin treatment had a molecular weight of about 96K. The heavy chain was split into 26 K, 50 K, and 21 K fragments by trypsin. When the trypsin-treated subfragment-1 was cross-linked with dimethyl suberimidate, cross-linked products of 26 K, 50 K, and 21 K fragments and of 50 K and 21 K fragments appeared, but there was little cross-linked product of 26 K and 50 K fragments or of 26 K and 21 K fragments. When the cross-linking experiments were carried out in the presence of actin, a new band appeared and the amount of cross-linked product of 26 K, 50 K, and 21 K fragments decreased by about 50%. The molecular weight of the new band was lower than that of the cross-linked product of 26 K, 50 K, and 21 K fragments, and higher than that of the dimer of actin. Based on this and some other results, we suggest that this band represented a cross-linked product of actin and the 50 K fragment. We also suggest that the decrease in the amount of cross-linked product of 26 K, 50 K, and 21 K fragments reflected the conformational change in subfragment-1 due to the binding of actin.
D000199:Actins; D000818:Animals; D001665:Binding Sites; D002918:Chymotrypsin; D004591:Electrophoresis, Polyacrylamide Gel; D046911:Macromolecular Substances; D008970:Molecular Weight; D009132:Muscles / Q000032:analysis; D009218:Myosins; D011485:Protein Binding; D011817:Rabbits; D014357:Trypsin
D000199:Actins; D046911:Macromolecular Substances; D002918:Chymotrypsin; D014357:Trypsin; D009218:Myosins