Mechanism of Catch Force: Tethering of Thick and Thin Filaments by Twitchin

Figure 9

Relationship between the fractional decrease in force caused by phosphorylation of twitchin and the total force (𝑃/𝑃_𝑜) before twitchin phosphorylation in permeabilized ABRM. Data for individual muscles are shown as the following: pCa 4.5, + 𝑃_𝑖 (⊡); pCa 5, control (), 𝑃_𝑖 5 mM (), 𝑃_𝑖 25 mM (), blebbistatin 1.25–25 𝜇M (∇); pCa 5.7, control (■), 𝑃_𝑖 5 mM (□); pCa 6, control (, ▲), 𝑃_𝑖 5 mM (○), BDM 10 mM (∆), TFP 200 𝜇M (⊙); pCa 6.3 (♦), 𝑃_𝑖 5 mM (); pCa 7, (▾). Mean ± SE (𝑁 = 16) for catch force remaining 10 minutes (), 20 minutes () after switch from pCa 6 to pCa > 8. The line is a least squares quadratic fit to the data. 𝑇 = 20 C. Reproduced from [98] with permission.