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. 1985 Jan 1;100(1):208–215. doi: 10.1083/jcb.100.1.208

Structure of C protein purified from cardiac muscle

PMCID: PMC2113476  PMID: 3838095

Abstract

C protein is a component of the thick filament of striated muscles. Although the function of C protein remains unknown, a variety of evidence suggests that C protein may regulate actin-myosin interaction or be involved in structural support or elasticity of the sarcomere. We have previously proposed (Hartzell, H. C., 1984, J. Gen. Physiol., 83:563-588) that C protein is involved in regulating twitch relaxation in cardiac muscle. To gain further insight into the function of C protein, we have studied the structure of C protein purified from chicken heart. C protein was purified from extracts of detergent-washed myofibrils by sequential hydroxylapatite and DEAE-Sephacel chromatography. C protein was judged greater than 95% pure by SDS PAGE. The polypeptide subunit had a molecular weight of 155,000 and the native molecule sedimented on linear sucrose or glycerol gradients at 4- 5S. For electron microscopy, purified C protein was dialyzed and diluted into a volatile buffer in 50% glycerol, aspirated onto mica, dried under vacuum, and rotary platinum-shadowed. Replicas revealed particles of relatively homogeneous overall dimensions. Over half of the particles were V-shaped. The "arm" lengths of the V-shaped particles were 22 +/- 4.5 nm (SD). Gel filtration on Sephacryl S-300 demonstrated that purified C protein had a Stokes' radius of 5.07 nm. Measurements of viscosity gave an intrinsic viscosity of 16.5 cm3/g. These data are consistent with the electron microscopic data and suggest that C protein in heart muscle is asymmetric. The C protein molecule is large enough to extend from the surface of a thick filament to adjacent thin or thick filaments.

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Selected References

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  1. Craig R., Offer G. The location of C-protein in rabbit skeletal muscle. Proc R Soc Lond B Biol Sci. 1976 Mar 16;192(1109):451–461. doi: 10.1098/rspb.1976.0023. [DOI] [PubMed] [Google Scholar]
  2. Craig R. Structure of A-segments from frog and rabbit skeletal muscle. J Mol Biol. 1977 Jan 5;109(1):69–81. doi: 10.1016/s0022-2836(77)80046-6. [DOI] [PubMed] [Google Scholar]
  3. Dennis J. E., Shimizu T., Reinach F. C., Fischman D. A. Localization of C-protein isoforms in chicken skeletal muscle: ultrastructural detection using monoclonal antibodies. J Cell Biol. 1984 Apr;98(4):1514–1522. doi: 10.1083/jcb.98.4.1514. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Elliott A., Offer G. Shape and flexibility of the myosin molecule. J Mol Biol. 1978 Aug 25;123(4):505–519. doi: 10.1016/0022-2836(78)90204-8. [DOI] [PubMed] [Google Scholar]
  5. England P. J. Cardiac function and phosphorylation of contractile proteins. Philos Trans R Soc Lond B Biol Sci. 1983 Jul 5;302(1108):83–90. doi: 10.1098/rstb.1983.0040. [DOI] [PubMed] [Google Scholar]
  6. Godfrey J. E., Harrington W. F. Self-association in the myosin system at high ionic strength. I. Sensitivity of the interaction to pH and ionic environment. Biochemistry. 1970 Feb 17;9(4):886–893. doi: 10.1021/bi00806a025. [DOI] [PubMed] [Google Scholar]
  7. Hartzell H. C. Phosphorylation of C-protein in intact amphibian cardiac muscle. Correlation between 32P incorporation and twitch relaxation. J Gen Physiol. 1984 Apr;83(4):563–588. doi: 10.1085/jgp.83.4.563. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Hartzell H. C., Titus L. Effects of cholinergic and adrenergic agonists on phosphorylation of a 165,000-dalton myofibrillar protein in intact cardiac muscle. J Biol Chem. 1982 Feb 25;257(4):2111–2120. [PubMed] [Google Scholar]
  9. Jeacocke S. A., England P. J. Phosphorylation of a myofibrillar protein of Mr 150 000 in perfused rat heart, and the tentative indentification of this as C-protein. FEBS Lett. 1980 Dec 15;122(1):129–132. doi: 10.1016/0014-5793(80)80418-2. [DOI] [PubMed] [Google Scholar]
  10. Julian F. J., Moss R. L., Sollins M. R. The mechanism for vertebrate striated muscle contraction. Circ Res. 1978 Jan;42(1):2–14. doi: 10.1161/01.res.42.1.2. [DOI] [PubMed] [Google Scholar]
  11. Koretz J. F., Coluccio L. M., Bertasso A. M. The aggregation characteristics of column-purified rabbit skeletal myosin in the presence and absence of C-protein at pH 7.0. Biophys J. 1982 Feb;37(2):433–440. doi: 10.1016/S0006-3495(82)84689-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
  13. Lowey S., Slayter H. S., Weeds A. G., Baker H. Substructure of the myosin molecule. I. Subfragments of myosin by enzymic degradation. J Mol Biol. 1969 May 28;42(1):1–29. doi: 10.1016/0022-2836(69)90483-5. [DOI] [PubMed] [Google Scholar]
  14. MARTIN R. G., AMES B. N. A method for determining the sedimentation behavior of enzymes: application to protein mixtures. J Biol Chem. 1961 May;236:1372–1379. [PubMed] [Google Scholar]
  15. Moos C., Feng I. N. Effect of C-protein on actomyosin ATPase. Biochim Biophys Acta. 1980 Oct 1;632(2):141–149. doi: 10.1016/0304-4165(80)90071-9. [DOI] [PubMed] [Google Scholar]
  16. Moos C., Mason C. M., Besterman J. M., Feng I. N., Dubin J. H. The binding of skeletal muscle C-protein to F-actin, and its relation to the interaction of actin with myosin subfragment-1. J Mol Biol. 1978 Oct 5;124(4):571–586. doi: 10.1016/0022-2836(78)90172-9. [DOI] [PubMed] [Google Scholar]
  17. Moos C., Offer G., Starr R., Bennett P. Interaction of C-protein with myosin, myosin rod and light meromyosin. J Mol Biol. 1975 Sep 5;97(1):1–9. doi: 10.1016/s0022-2836(75)80017-9. [DOI] [PubMed] [Google Scholar]
  18. Morimoto K., Harrington W. F. Substructure of the thick filament of vertebrate striated muscle. J Mol Biol. 1974 Feb 15;83(1):83–97. doi: 10.1016/0022-2836(74)90425-2. [DOI] [PubMed] [Google Scholar]
  19. Offer G., Moos C., Starr R. A new protein of the thick filaments of vertebrate skeletal myofibrils. Extractions, purification and characterization. J Mol Biol. 1973 Mar 15;74(4):653–676. doi: 10.1016/0022-2836(73)90055-7. [DOI] [PubMed] [Google Scholar]
  20. Pepe F. A., Drucker B. The myosin filament. III. C-protein. J Mol Biol. 1975 Dec 25;99(4):609–617. doi: 10.1016/s0022-2836(75)80175-6. [DOI] [PubMed] [Google Scholar]
  21. Rome E., Offer G., Pepe F. A. X-ray diffraction of muscle labelled with antibody to C-protein. Nat New Biol. 1973 Aug 1;244(135):152–154. doi: 10.1038/newbio244152a0. [DOI] [PubMed] [Google Scholar]
  22. Shotton D. M., Burke B. E., Branton D. The molecular structure of human erythrocyte spectrin. Biophysical and electron microscopic studies. J Mol Biol. 1979 Jun 25;131(2):303–329. doi: 10.1016/0022-2836(79)90078-0. [DOI] [PubMed] [Google Scholar]
  23. Starr R., Offer G. Preparation of C-protein, H-protein, X-protein, and phosphofructokinase. Methods Enzymol. 1982;85(Pt B):130–138. doi: 10.1016/0076-6879(82)85016-7. [DOI] [PubMed] [Google Scholar]
  24. Starr R., Offer G. The interaction of C-protein with heavy meromyosin and subfragment-2. Biochem J. 1978 Jun 1;171(3):813–816. doi: 10.1042/bj1710813. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Tyler J. M., Branton D. Rotary shadowing of extended molecules dried from glycerol. J Ultrastruct Res. 1980 May;71(2):95–102. doi: 10.1016/s0022-5320(80)90098-2. [DOI] [PubMed] [Google Scholar]
  26. Yamamoto K., Moos C. The C-proteins of rabbit red, white, and cardiac muscles. J Biol Chem. 1983 Jul 10;258(13):8395–8401. [PubMed] [Google Scholar]

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