Fig. 1: Study of MyBP-C in skeletal muscle by targeted, acute and specific cleavage in situ.
a Schematic of a skeletal half-sarcomere. b Expanded view of crown placement on thick filaments. c Schematic of one ~43 nm repeat in the C-zone, with crowns shown in the structural OFF and ON states (details in text). Arrows indicate the suggested interactions between different elements29,31,51. d Domain layout of fast and slow twitch MyBP-C, with the TEV protease cleavage site of SNOOPC2 mouse line indicated. e Western blot of tagged fast MyBP-C isoform (fMyBP-C) from homozygous and wildtype SNOOPC2 psoas, before and after fast isoform cleavage (fMyBP-CC1C7—cleaved N-terminal domains). The experiment was repeated 3 times for the HOM condition and 1 time for WT. f–m Mechanical measurements of permeabilized psoas fibers from SNOOPC2 muscle, before (−) and after (+) TEV protease treatment (N-terminal domains removed) for passive tension-SL (f), relative tension-pCa curves at 2.4 (g), 2.7 (h), and 3.0 µm (i) SL, representative tension ktr curves before and after TEV protease treatment, (j) and normalized ktr vs. relative tension at 2.4 (k), 2.7 (l), and 3.0 µm (m) SL. Statistics throughout are repeated-measures ANOVA designs followed by a Tukey honestly significant difference (HSD) post-hoc test on statistically significant main effects. *P < 0.05 after treatment at each SL. Stats in (k, f–m) are reported via connecting letters, where conditions with different letters are significantly different. Data throughout was reported as mean ± SE. Experimental dataset derived from 49 fiber bundles from psoas muscles of 10 SNOOPC2 mice (6 female/4 male). Further descriptive and statistical details are in Supplementary Tables 1–8. Created with BioRender.com.
