Figure 1.

Cardiac myosin isoforms and PKA-induced phosphorylation of sarcomeric proteins. A: mice were hypothyroid after 12 wk of PTU diet and expressed 100% β-cardiac myosin in the LV at time of harvest. B: gels show comparable protein loads. The lane marked myosin provides a reference for myosin and its contaminants of MyBP-C and actin. The lane loaded with isolated troponin (Trpn) with its three components provides reference for TnT, TnC, and particularly phosphorylatable TnI at ∼24 kDa. C: Pro-Q diamond phospho-stain demonstrates that PKA treatment led to significant phosphorylation of TnI in both genotypes. Phosphorylation of cMyBP-C was not as visually apparent and was quantified instead by mass spectrometry (see Table 1). PKA, protein kinase A; PTU, 6-propyl-2-thiouracil.