Fig. 8: Thin filament structure assessed by X-ray diffraction on intact EDL muscle.

a Experimental setup. b X-ray diffraction images with examined reflections indicated. Left image taken during rest and Right image is the difference between active and passive muscle. (See Methods for details.) c The spacing change of the 13th actin meridional reflection (27 Å), during tetanic force development, is identical in both genotypes. d Thin filament stiffness is identical in both genotypes (for calculations, see Supplementary Fig. 6b, c and Results). e Short(left) - and long(right)-pitch helical periodicity of the actin filament. The long-pitch helix (right) is significantly reduced (p = 0.0025) in the Compound-Het. f The actin radius, determined from the radial spacing of the ALL6, is increased in Compound-Het. g The intensity change of the second actin layer line (due to tropomyosin) and h the intensity of the third meridional troponin reflection upon activation, are both reduced in the Compound-Het EDL muscle (P = 0.0089 and p = 0.044., respectively). i Thin-thick filament spacing (2/3 x d1,0) is increased in compound Het, both in the relaxed and active states. (Based on d1,0 data in Supplementary Fig. 6a) Number of mice: WT: 15, Compound-HET: 11. For some animals both EDL muscles were used. Number of muscles: WT: 18, Compound-HET: 14. Bars and lines are mean ± SEM. c–h two-tailed unpaired t-test. *p < 0.05;**p < 0.01; ****p < 0.0001. h Ordinary one-way ANOVA without matching or paring. A posthoc multiple testing comparison with multiple testing correction (Tukey) was performed. ****p < 0.0001. Source data are provided as a Source Data file.