RNA Purification and Isolation

Isolating high-quality RNA molecules is crucial to many downstream experiments, such as cloning, reverse transcription for cDNA synthesis, RT-PCR, RT-qPCR and RNA-seq. There are various approaches to RNA purification including phenol-chloroform extraction, spin column purification, and the use of magnetic beads.

Total RNA purification involves the extraction and purification of total RNA from your sample, for use in gene expression analyses such as RT-qPCR or RNA-seq. Depending on the starting sample, different protocols should be employed to most efficiently lyse cells or tissues, and purify the RNA from contamination genomic DNA and other cellular components. Theoretically, total RNA purification involves the isolation of all of the cellular RNA, including various sizes ranging from intact ribosomal RNA down to small RNA (including miRNA, tRNA and 5sRNA).

For recovery of a specific RNA subpopulation from total RNA derived from cells, tissues or in vitro transcriptions, bead-based methods may be utilized to isolate mRNAs through binding of the poly(A) tail or to isolate RNAs based on size by varying the ratio of nucleic acid to beads in the presence of a crowding reagent. Bead-based methods are a rapid way to isolate RNA free from enzymes, salts and nucleotides from a variety of sources, and when RNA is present at lower concentrations.

In vitro transcribed RNA also often needs to be cleaned up and separated from components such as DNA templates, unincorporated nucleotides or RNA modifying enzymes. Chemical-, column- and gel-based approaches can be used, and are sometimes combined to result in purified RNA free from nucleotides, salts and proteins. Learn more  about cleaning up in vitro transcribed RNA.

Regardless of the methods employed, purified RNA is ready for use in various downstream applications including expression analysis, transient transfections or microinjections to assess genome editing or RNA localization, as well as in vitro assays including RNA structure studies, nucleic acid hybridizations and in vitro translation.