VELUCT, a long non-coding RNA with an important cellular function despite low abundance
With the completion of the human genome project, it has become obvious that protein-coding genes comprise only 2% of the genome, although the majority of the genome is transcribed into RNA. RNA molecules that lack protein-coding potential are collectively referred to as non-coding (nc) RNAs. In addition to the well-known housekeeping rRNAs, tRNAs and small nuclear RNAs (snRNAs), the most intensively studied subgroup of ncRNAs are the microRNAs (miRNAs), which are well characterized by their size and uniform function. Another distinct class of ncRNAs, long ncRNAs (lncRNAs), are larger than 200 nucleotides. They are markedly heterogeneous in size and cellular function. While the number of annotated lncRNA genes in the human genome outnumbers protein-coding genes (1), studies of their functional roles and detailed mechanisms account for less than 0.1% of all predicted lncRNAs (2).