Fig. 2. Quantitative proteome differences between slow- and fast-twitch muscle fibers.

a Principal component analysis (PCA) separating slow- and fast-twitch fibers in two groups. b PCA loading displaying selected examples of the most abundant proteins. c Volcano plot comparing protein abundance in slow- and fast-twitch muscle fibers. Differently regulated proteins (significance score ≤0.05; paired linear model with Xiao correction⁷²) are marked in blue (high in fast-twitch fiber) and red (high in slow-twitch fiber). d Hierarchical clustering of significantly different proteins (left) and Fischer exact test for enrichment analysis of significantly different proteins (right). e Graphical representation of a myofibril. f Comparative protein abundance of Terminal cisternae, sarcoplasmic reticulum (SR), T-tubule, and Ca²⁺ channel complex in slow- and fast-twitch fibers. g Major organelle protein composition in slow- and fast-twitch muscle fibers. Data in f, g are shown as median. P values by two-tailed paired t-test are indicated in f, g.