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. 2024 Jun 25;121(27):e2400497121. doi: 10.1073/pnas.2400497121

Fig. 6.

Fig. 6.

Interactions between endogenous S100A1 and RyR channels. (A) Confocal coimmunofluorescence images of S100A1 (red) and RyR2 (green) in skeletal myofibers (green) isolated from mouse EDL muscles. RyR1 exhibited a cross-striated pattern typical for the junctional sarcoplasmic reticulum and partially overlapping with S100A1. Dashed boxes indicate magnification shown below. Scale bar, 10 µm (Top) and 1 µm (Bottom). (B) Ca2+ dependency of coimmunoprecipitations (IP) between endogenous RyR channels and S100A1 versus CaM. RyR complexes were immunoprecipitated from skeletal muscle, heart muscle, and cerebellar lysates at indicated free [Ca2+] followed by immunoblotting against RyR, S100A1, and CaM. (C) Quantification of bound S100A1 and CaM in the IPs of RyR1 from the skeletal muscle. The relative abundance of S100A1/RyR1 (Left) and CaM/RyR1 (Right) is plotted against free [Ca2+] (mean ± SD; n = 8 per group) showing a tendentiously stronger Ca2+ dependence of the endogenous S100A1–RyR1 interaction compared to CaM. Two-tailed Student’s t test; *P < 0.05, **P < 0.01, ***P < 0.001.