PolyA

Poly (A)  Polyadenylic acid Carrier RNA

Poly(A), or polyadenylic acid, is a homopolymer of adenylic acid. Poly(A) is enzymatically added to messenger RNA (mRNA) in eukaryotic cells to stabilize mRNAs. Bio-Synthesis provides poly (A) carrier RNA ranging in size from 200 to 10,000 base pairs. Adding carrier poly A nucleic acids or carrier RNA to extraction buffers increases the yield of extracted DNA and RNA from analytical samples. Polyadenylic acid (Poly (A)) used as a carrier molecule ensures success for many molecular biology methods. Poly (A) used as a coprecipitant stabilizes extracted pathogenic RNA as well as synthetic RNA or DNA including large oligonucleotide molecules. Adding poly (A) to extraction buffers improves the recovery of low amounts of RNA.

Many commercial purification protocols or kits for the extraction of low levels of RNA from biological samples now recommend the use of a carrier molecule such as poly (A).

Reference:

• Shaw et al., in 2009, showed that the addition of poly-A carrier RNA to the chaotropic salt solution increases the recovery of RNA. The researchers observed that the use of nucleic acid carrier molecules enhances DNA extraction methods in microfluidic applications.
• Shaw KJ, Thain L, Docker PT, et al. The use of carrier RNA to enhance DNA extraction from microfluidic-based silica monoliths. Anal Chim Acta. 2009;652(1-2):231-233. doi:10.1016/j.aca.2009.03.038 {Pubmed}
• A poly (A) carrier is also very useful for the stabilization of other RNA molecules, for example, for gene editing studies. Miyaoka et al. employed a poly (A) carrier when quantifying the repair of double-strand breaks during homology-directed repair. 
• Miyaoka Y, Berman JR, Cooper SB, et al. Systematic quantification of HDR and NHEJ reveals effects of locus, nuclease, and cell type on genome-editing. Sci Rep. 2016;6:23549. Published 2016 Mar 31. doi:10.1038/srep23549. {Pubmed}