Fig. 9. Myofilament Ca²⁺ sensitivity is altered in aging.

a Western blot of total (top) and pS23/24 (bottom) cTnI expression in whole heart lysates from young, old, shRNA-mBIN1 or shRNA-scrmb transduced mice. Ponceau was used for normalization. b Histogram showing normalized total cTnI levels relative to young (N = 3 biological replicates). c Histogram showing cTnI pS23/24 normalized to total cTnI relative to young (N = 3 biological replicates). d Western blot of total (top) and pS273 (bottom) cMyBP-C expression in whole heart lysates from young, old, shRNA-mBIN1 or shRNA-scrmb transduced mice. Ponceau was used for normalization. e Histogram showing normalized total cMyBP-C levels relative to young (N = 3 biological replicates). f Histogram showing cMyBP-C pS273 normalized to total cMyBP-C relative to young (N = 3 biological replicates). Statistical analysis was performed on data in (b, c, e, f ) using one-way ANOVAs with multiple comparisons post-hoc test. Young data are from JAX young mice. Note there was no significant difference in cTnI (total and pS23/24) or cMyBP-C (total and pS273) expression when JAX and NIA-sourced young mice were compared (see Supplementary Fig. 1m–r). Data are presented as mean ± SEM. See Supplemental Information for uncropped scans and number of technical replicates for western blots. Source data are provided in the Source Data file.