title: Direct cross-linking of three domains in the myosin head.
abstract: To obtain information about domain-domain contacts in the myosin head, trypsin-split myosin subfragment-1 (S-1), which mainly consists of 50K, 26K, and 20K fragments, was cross-linked directly by the photodynamic technique under mild conditions (pH 7-8.5, 0 degrees C) using riboflavin 5'-phosphate, protoporphyrin, and methylene blue as sensitizers. Exposure of trypsin split-chymotryptic S-1 to visible light in the presence of the sensitizers resulted in formation of cross-linked products of (20 + 26)K, (20 + 50)K, (26 + 50)K, and (20 + 26 + 50)K fragments. The results suggest that three domains in the myosin head are in contact with each other, at least partly, raising the possibility that the communication between the ATP- and actin-binding sites passes through a "short cut," i.e., the contact region between the domains.
mesh_terms: D000199:Actins; D000255:Adenosine Triphosphate; D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D008970:Molecular Weight; D009132:Muscles; D015879:Myosin Subfragments; D009218:Myosins; D010446:Peptide Fragments; D010777:Photochemistry; D011817:Rabbits; D014357:Trypsin
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D010446:Peptide Fragments; D000255:Adenosine Triphosphate; D014357:Trypsin; D009218:Myosins