Figure 1.
Expression levels are correlated with peptide detectability via MS/MS. Peptide detectability (y-axis) as a function of RNA expression levels (RPKM, x-axis) in GM12878 (A) and K562 (B) whole-cell RNA samples. We identified peptides for only 1% of genes expressed at RPKM <0.1, whereas we detected peptides for ∼40% of genes expressed above RPKM 100. In general, the likelihood of detection rises as expression level rises.
