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. 2021 Mar 5;320(5):H1822–H1835. doi: 10.1152/ajpheart.00673.2020

Figure 6.

Figure 6.

Effect of cMyBP-C, Pi, and PKA on myosin cross-bridge kinetics in skinned myocardial strips. A: the rate of force development (2πb) at maximum calcium activation (pCa 4.8) was significantly enhanced by a lack of cMyBP-C and by increasing Pi. The sensitivity of 2πb to Pi was furthermore enhanced by the absence of cMyBP-C. These data suggest that cMyBP-C inhibits β-cardiac myosin cross-bridge kinetics including those dependent upon Pi. PKA also enhanced 2πb at pCa 4.8 although subtly. B: myosin cross-bridge detachment rate (2πc) at pCa 4.8 was enhanced by a lack of cMyBP-C and by increasing Pi. The Pi sensitivity of 2πc was further enhanced by a lack of cMyBP-C. C and D: results for 2πb and 2πc at submaximal calcium activation mirrored those at pCa 4.8 with enhancement due to lack of cMyBP-C and with increasing Pi. The sensitivity of 2πb and 2πc to Pi was further enhanced when cMyBP-C was absent. Means ± SE. cMyBP-C, cardiac myosin binding protein-C; NTGβ, nontransgenic; t/tβ, transgenic lacking cMyBP-C; PKA, protein kinase A.