Fig. 1

EDL, psoas, and soleus constitute unique expression signatures. a Expression of the four primary myosin isoforms in EDL, psoas, and soleus. Both EDL and psoas predominantly express Myh-2B (Myh4) isoform, while soleus expresses nearly equivalent levels of Myh-1(Myh7), Myh-2A(Myh2), and Myh-2X(Myh1). b Percent Myh isoform expression in mouse EDL, psoas, and soleus from the present study (red) agree well with the proteomics and transcriptomics data gathered from the literature (black). Percent Myh isoform expression was calculated as a fraction of total FPKM values of Myh1, Myh2, Myh4, and Myh7, and compared to the data reported by previous publications using t-tests. Data used to carry out the statistical analysis, and the results are shown in Table S2 in SI. At the 95% significant level, no significant expression difference was observed between the two datasets (c) PCA after filtering-out marginally expressed genes (see methods for the selection criteria used). PC1 identifies 46% of the expression variability among genes and creates two major clusters separating fast muscles (EDL and psoas) from slow muscle (soleus). PC2 accounts for 27% of the variance and separates EDL, psoas, and soleus into three distinct clusters. d UpSet plot showing the number of unique and overlapping genes between the up and down-regulated genes identified by the pairwise comparison of EDL, psoas, and soleus. The total number of uniquely differentially expressed genes between two fast muscles is greater than that of the fast to slow comparisons