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Description: To annotate the exosomal RNA species that were not identified as miRNA transcripts, we first removed all the known miRNA sequences from the libraries and then mapped the remaining sequences to the human genome that had RNA annotations. Figure 5A shows the percentage of other small non-coding RNAs, tRNA, rRNA, small nuclear (snRNA), small nucleolar (snoRNA) and piwi-interacting RNA (piRNA) that were detected. The rRNA was the most common among them, accounting for 9.16% of all mappable counts, followed by piRNA (1.31%), tRNA (1.24%), snRNA (0.18%), and snoRNA (0.01%). Clearly, the exosomes contained relatively low levels of rRNA, which is in contrast to a typical eukaryotic cell where rRNA makes up at least 80% of the total RNA molecules. Interestingly, we also detected low levels of long RNA in the small RNA libraries. We detected 3.36% of long non-coding RNA (lncRNA), 1.36% of coding sequences (CDS), 0.54% of 3'untranslated region (UTR) and 0.21% of 5'UTR sequences [see Additional file 3]. Data are collected from Additional file 3: Top 20 RNAs in other RNA species (normalized to read number per million all mappable RNA seqeuences).
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