Polarization microfluorimetry study of interaction between myosin head and F-actin in muscle fibers.
Changes in conformation of F-actin induced by the binding of myosin molecule subfragment 1 were studied in myosin-free single ghost muscle fibers with the method of polarization microfluorimetry. The modification of the structure of subfragment 1 by proteolytic digestion with one or two cuts in subfragment 1 or degradation of 50 kDa domain did not influence the character of changes in the conformation of F-actin. The use of preparations of subfragment 1 devoid of the 20 kDa domain or both cross-linked SH1 and SH2-groups changed the character of conformational rearrangements in F-actin. The present data show that a site of interaction with actin in the 20 kDa domain plays a key role in inducing the changes in actin conformation corresponding to a "strong" form of the binding. It is supposed that transmission of changes in the conformation of the myosin head to F-actin might be important for muscle contraction.
Borovikov YuS
Institute of Cytology, Academy of Sciences of the USSR, Sankt-Peterburg.
Kuleva
N V
NV
Khoroshev
M I
MI
D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D003592:Cytophotometry; D004591:Electrophoresis, Polyacrylamide Gel; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D009119:Muscle Contraction; D009132:Muscles / Q000737:chemistry*; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism; D009282:Naphthalenesulfonates; D010590:Phalloidine; D011487:Protein Conformation; D011817:Rabbits; D012235:Rhodamines
D000199:Actins; D005456:Fluorescent Dyes; D009282:Naphthalenesulfonates; D012235:Rhodamines; D010590:Phalloidine; C006421:1,5-I-AEDANS; D000251:Adenosine Triphosphatases; D009218:Myosins