Effects of C-protein on synthetic myosin filament structure.
In the absence of C-protein, synthetic filaments prepared from column-purified myosin exhibit the following features: individual filament diameters are uniform over a long length, but a wide distribution of diameters is apparent over the population; approximately 25% of the filaments have a frayed appearance and take up stain poorly, whereas the remaining 75% are well-stained; optical diffraction of well-stained filaments reveals a 14.3-nm subunit period and a 43-nm axial period (Koretz, 1978; Koretz, 1979). Addition of C-protein to myosin before filament formation affects all of these features in a manner related to C-protein concentration. At the physiological ratio of C-protein to myosin in the banded region of the natural thick filament, synthetic aggregates are uniform in diameter over the population and show less than 10% frays. Whereas the subunit period remains unchanged, the axial period has increased to 114.4 nm, or eight times the subunit repeat. Above and below the physiological ratio, disorder of a specific nature is apparent. Addition of C-protein after filament formation appears to coat the aggregates so that elements of backbone ultrastructure are obscured, and some evidence of axial period change is visible in diffraction patterns. A model is presented for the binding of C-protein to myosin, and its observed effects on filament structure are explained in terms of this model.
D002352:Carrier Proteins; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003599:Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure*; D003956:Dialysis; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000494:pharmacology*; D009218:Myosins / Q000302:isolation & purification; D000099163:Myosin Binding Protein C
D002352:Carrier Proteins; D009124:Muscle Proteins; D009218:Myosins; D000099163:Myosin Binding Protein C
Biochem J. 1978 Jun 1;171(3):813-6
352343
J Cell Biol. 1977 Jul;74(1):136-52
326798
J Mol Biol. 1975 Dec 25;99(4):609-17
814246
J Mol Biol. 1971 Jun 28;58(3):865-71
4103927
J Cell Biol. 1975 Oct;67(1):93-104
1236853
J Mol Biol. 1977 Jun 15;113(1):199-218
881734
FEBS Lett. 1971 Jun 2;15(1):40-44
11945810
Nat New Biol. 1973 Aug 1;244(135):152-4
4516378
J Mol Biol. 1974 Feb 15;83(1):83-97
4817801
J Mol Biol. 1975 Sep 5;97(1):1-9
1100851
J Mol Biol. 1967 Dec 14;30(2):383-434
5586931
J Mol Biol. 1973 Mar 15;74(4):653-76
4269687
J Mol Biol. 1973 Jun 15;77(1):165-75
4769837
Biophys J. 1979 Sep;27(3):423-32
263630
J Mol Biol. 1975 Feb 15;92(1):113-43
1080204
Proc R Soc Lond B Biol Sci. 1976 Mar 16;192(1109):451-61
4802