Myosin binding to actin. Structural analysis using myosin fragments.
The actin-binding property of the myosin head 20 K (K = 10(3) Mr) fragment has been examined by a structural assay. A new fragment is produced by digestion of scallop myosin synthetic filaments with a lysine-specific protease. This fragment consists of the rod together with two "nubs" corresponding to the 20 K fragment, which retain both the regulatory and essential light chains. Myosin filaments, digested for different lengths of time, were mixed with F-actin and visualized by electron microscopy after negative staining. When the head is cleaved, but the head fragments remain associated, the filaments bind actin in an ATP-sensitive manner. Filaments made primarily of the nub-containing fragments, however, bind actin very poorly. In addition, electron microscopic characterization of actin-binding by the isolated tryptic 20 K fragment from chicken myosin indicates that binding of this fragment to actin is probably non-specific. These results suggest that interactions between the 20 K region and the other peptides in the head are essential for actin-binding.
Castellani
L
L
Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02254.
Elliott
B W
BW
Winkelmann
D A
DA
Vibert
P
P
Cohen
C
C
D000199:Actins / Q000378:metabolism*; D000818:Animals; D008854:Microscopy, Electron; D015879:Myosin Subfragments; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism
D000199:Actins; D015879:Myosin Subfragments; D010446:Peptide Fragments; D009218:Myosins