Calcium dependence of force and structural parameters
| . | nH . | pCa50 . |
|---|---|---|
| Force (fiber bundles) | 2.63 ± 1.43 | 5.99 ± 0.17 |
| I11/I10 | 4.72 ± 1.52 (P = 0.096) | 6.18 ± 0.05 (P = 0.089) |
| d10 | 2.88 ± 0.97 (P = 0.422) | 6.40 ± 0.10 (P = 0.013) |
| IML1 | 3.53 ± 1.83 (P = 0.265) | 6.56 ± 0.14 (P = 0.004) |
| AML1 | 2.93 ± 1.94 (P = 0.430) | 6.49 ± 0.10 (P = 0.007) |
| SM6a | 2.58 ± 0.48a | 6.18 ± 0.03a |
| SM3 | 5.11 ± 1.37 (P = 0.037) | 6.24 ± 0.02 (P = 0.041) |
| IM3 | 4.34 ± 2.09 (P = 0.046) | 6.07 ± 0.09 (P = 0.251) |
| AM3 | 4.17 ± 1.77 (P = 0.064) | 6.13 ± 0.07 (P = 0.144) |
| LM3 | 3.45 ± 1.52 (P = 0.205) | 6.22 ± 0.03 (P = 0.039) |
| IM1 | 4.25 ± 1.05 (P = 0.119) | 6.55 ± 0.06 (P = 0.005) |
| IM2H | 4.10 ± 1.63 (P = 0.038) | 6.65 ± 0.06 (P = 0.003) |
| IM2L | 3.60 ± 1.30 (P = 0.117) | 6.63 ± 0.09 (P = 0.008) |
| AM2H | 3.88 ± 1.85 (P = 0.044) | 6.59 ± 0.04 (P = 0.003) |
| AM2L | 3.14 ± 1.91 (P = 0.221) | 6.54 ± 0.07 (P = 0.006) |
| IT1 | 6.12 ± 1.65 (P = 0.009) | 6.61 ± 0.08 (P = 0.007) |
| AT1 | 7.00 ± 1.11 (P = 0.003) | 6.59 ± 0.09 (P = 0.008) |
| ForceSS (single fibers) | 4.31 ± 0.55 | 6.43 ± 0.01 |
| <P2>SS (single fibers) | 5.80 ± 0.17 | 6.53 ± 0.01 |
| ForceTj (single fibers) | 3.82 ± 0.32 (P = 0.935)b | 6.37 ± 0.01 (P = 0.157)b |
| <P2>Tj (single fibers) | 6.94 ± 0.87 (P = 0.596)b | 6.49 ± 0.01 (P = 0.510)b |
| . | nH . | pCa50 . |
|---|---|---|
| Force (fiber bundles) | 2.63 ± 1.43 | 5.99 ± 0.17 |
| I11/I10 | 4.72 ± 1.52 (P = 0.096) | 6.18 ± 0.05 (P = 0.089) |
| d10 | 2.88 ± 0.97 (P = 0.422) | 6.40 ± 0.10 (P = 0.013) |
| IML1 | 3.53 ± 1.83 (P = 0.265) | 6.56 ± 0.14 (P = 0.004) |
| AML1 | 2.93 ± 1.94 (P = 0.430) | 6.49 ± 0.10 (P = 0.007) |
| SM6a | 2.58 ± 0.48a | 6.18 ± 0.03a |
| SM3 | 5.11 ± 1.37 (P = 0.037) | 6.24 ± 0.02 (P = 0.041) |
| IM3 | 4.34 ± 2.09 (P = 0.046) | 6.07 ± 0.09 (P = 0.251) |
| AM3 | 4.17 ± 1.77 (P = 0.064) | 6.13 ± 0.07 (P = 0.144) |
| LM3 | 3.45 ± 1.52 (P = 0.205) | 6.22 ± 0.03 (P = 0.039) |
| IM1 | 4.25 ± 1.05 (P = 0.119) | 6.55 ± 0.06 (P = 0.005) |
| IM2H | 4.10 ± 1.63 (P = 0.038) | 6.65 ± 0.06 (P = 0.003) |
| IM2L | 3.60 ± 1.30 (P = 0.117) | 6.63 ± 0.09 (P = 0.008) |
| AM2H | 3.88 ± 1.85 (P = 0.044) | 6.59 ± 0.04 (P = 0.003) |
| AM2L | 3.14 ± 1.91 (P = 0.221) | 6.54 ± 0.07 (P = 0.006) |
| IT1 | 6.12 ± 1.65 (P = 0.009) | 6.61 ± 0.08 (P = 0.007) |
| AT1 | 7.00 ± 1.11 (P = 0.003) | 6.59 ± 0.09 (P = 0.008) |
| ForceSS (single fibers) | 4.31 ± 0.55 | 6.43 ± 0.01 |
| <P2>SS (single fibers) | 5.80 ± 0.17 | 6.53 ± 0.01 |
| ForceTj (single fibers) | 3.82 ± 0.32 (P = 0.935)b | 6.37 ± 0.01 (P = 0.157)b |
| <P2>Tj (single fibers) | 6.94 ± 0.87 (P = 0.596)b | 6.49 ± 0.01 (P = 0.510)b |
Mean Hill equation parameters (nH and pCa50) corresponding to the fits shown in Figs 1, 2, 3, 4, 5, 6, 7, and 8; and Fig. S3, with SD calculated from the fits of data from individual bundles. P values for nH and pCa50 are the results of paired t-tests between force and x-ray structural parameters. Force and <P2> values from fluorescence polarization experiments on single fibers exchanged with an RLC E-helix probe were obtained using either a conventional preactivation protocol at 25°C (steady state, SS; data from Fusi et al. [2016]) or the temperature jump protocol (Tj).
Due to lower signal-to-noise, Hill equation parameters for SM6 were obtained from the average meridional intensity distributions for four bundles, and SD was obtained from the fitting program.
P values from unpaired t-tests between force or <P2> in steady state and temperature jump protocols.