Myosin binding protein C phosphorylation in normal, hypertrophic and failing human heart muscle

J Mol Cell Cardiol. 2008 Aug;45(2):209-16. doi: 10.1016/j.yjmcc.2008.05.020. Epub 2008 Jun 4.


Phosphorylation of myosin binding protein C (MyBP-C) was investigated in intraventricular septum samples taken from patients with hypertrophic cardiomyopathy undergoing surgical septal myectomy. These samples were compared with donor heart muscle, as a well-characterised control tissue, and with end-stage failing heart muscle. MyBP-C was partly purified from myofibrils using a modification of the phosphate-EDTA extraction of Hartzell and Glass. MyBP-C was separated by SDS-PAGE and stained for phosphoproteins using Pro-Q Diamond followed by total protein staining using Coomassie Blue. Relative phosphorylation level was determined from the ratio of Pro-Q Diamond to Coomassie Blue staining of MyBP-C bands as measured by densitometry. We compared 9 myectomy samples and 9 failing heart samples with 9 donor samples. MyBP-C phosphorylation in pathological muscle was lower than in donor (myectomy 40+/-2% of donor, P<0.0001; failing 45+/-3% of donor, P<0.0001). 6 myectomy samples were identified with MYBPC3 mutations, one with MYH7 mutation and two remained unknown, but there was no correlation between MYBPC3 mutation and MyBP-C phosphorylation level. In order to determine the number of phosphorylated sites in human cardiac MyBP-C samples, we phosphorylated the recombinant MyBP-C fragment, C0-C2 (1-453) with PKA using (gamma32)P-ATP up to 3.5 mol Pi/mol C0-C2. This measurement of phosphorylation was used to calibrate measurements of phosphorylation in SDS-PAGE using Pro-Q Diamond stain. The level of phosphorylation in donor heart MyBP-C was calculated to be 4.6+/-0.6 mol Pi/mol and 2.0+/-0.3 mol Pi/mol in myectomy samples. We conclude that MyBP-C is a highly phosphorylated protein in vivo and that diminished MyBP-C phosphorylation is a feature of both end-stage heart failure and hypertrophic cardiomyopathy.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cardiomyopathy, Hypertrophic / genetics
  • Cardiomyopathy, Hypertrophic / metabolism*
  • Cardiomyopathy, Hypertrophic / pathology
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Heart Failure / genetics
  • Heart Failure / metabolism*
  • Heart Failure / pathology
  • Humans
  • Myocardium / metabolism*
  • Myocardium / pathology
  • Myosins / metabolism*
  • Phosphorylation


  • Carrier Proteins
  • myosin-binding protein C
  • Myosins