Fig. S9.

Intracellular localization of matched and unmatched mRNA. The subcellular localization of the mRNA also may affect the sampling efficiency. To examine this issue, we assume that the mRNA is localized to the same regions as the proteins they code for (3). We then compared the protein localization in 12 subcellular locations of the specific unmatched gene to the matched gene. mRNAs that code for proteins found in the plasma membrane were statistically shown to be unmatched more often (P < 0.05, t test), indicating that the specific mRNA sequences are more likely to be immobilized within the cytoplasm, resulting in a low detection rate.