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. 2017 Jan 24;112(2):376–387. doi: 10.1016/j.bpj.2016.12.013

Figure 4.

Figure 4

SL and Ca2+-independent tension of control, D137L, and D137L/G126R ααTm-reconstituted myofibrils. (A) Average SL-resting-tension relationships of myofibrils extracted and reconstituted with control (white square), D137L (light gray square), or D137L/G126R (dark gray square) ααTm. Data points at different SLs are means ± SEM (vertical and horizontal bars) of resting-tension values measured in five to nine individual myofibrils. Inset, lower trace: representative trace of 30% l0 step release applied to a myofibril at pCa 9.0; upper traces: Ca2+-independent force response for control ααTm and D137L ααTm mounted myofibrils. Tension calibration (vertical bar): 40 mN mm−2; time calibration (horizontal bar): 50 ms. (B) Effect of 10 mM BDM on average SL-resting-tension relationships for the different groups of Tm-Tn-replaced myofibrils. (C) Mean slack SL of free control, D137L, and D137L/G126R Tm-reconstituted myofibrils measured in relaxing solution. The SLs in the presence of mutant ααTm are significantly shorter compared with control ααTm myofibrils (∗p < 0.0001). SLs are also considerably shorter in D137L/G126R ααTm myofibrils than in D137L ααTm myofibrils (# p < 0.01). (D) Effect of 10 mM BDM on the mean slack SLs of control, D137L, and D137L/G126R ααTm-reconstituted myofibrils. All values (μm) are given as mean ± SEM: control ααTm 2.08 ± 0.02, control + BDM 2.13 ± 0.02; D137L ααTm 1.95 ± 0.02, D137L + BDM 2.10 ± 0.02; D137L/G126R ααTm 1.83 ± 0.03, D137L/G126R + BDM 2.07 ± 0.03. The number of myofibrils is given above the bars.