RNA Pull-Down Methods Compared

Team Dynamic Matrices | 31 August 2026

RNA pull-down means isolating a specific RNA, or whatever is bound to it, from a complex mixture. That covers mapping RNA-protein interactions, purifying an RNP for structural work, enriching a target for sequencing, and validating an interaction found by another method. The four main approaches differ in what they use as bait, how they capture, and how they let go. One of the four is ours, and we will say plainly where the others are the better choice.

Method 1: Biotinylated probe with streptavidin beads

Antisense DNA or RNA oligonucleotides carrying biotin hybridise to the target RNA; streptavidin beads pull down the hybrid; bound proteins or the RNA itself are eluted. ChIRP (Chu et al., Molecular Cell, 2011) and CHART (Simon et al., PNAS, 2011) are the tiled-probe versions for chromatin-associated RNAs.

Strengths: Well established, broadly trusted, works for any RNA with a known sequence.
Weaknesses: Bead surfaces adsorb non-specifically, so background scales with bead amount. Probe design is constrained by secondary structure and by regions shared with other transcripts. Elution from streptavidin needs boiling in SDS or formamide, which destroys native complexes; for the RNA alone that is fine, for bound proteins it is not.

Method 2: RNA immunoprecipitation (RIP)

An antibody against an RNA-binding protein captures the protein and whatever RNA it holds. CLIP variants add UV crosslinking for direct-contact resolution (Ule et al., Science, 2003; König et al., Nature Structural and Molecular Biology, 2010).

Strengths: The right tool when the question is "what does this protein bind". Rich literature.
Weaknesses: Entirely dependent on antibody quality and specificity; many RBP antibodies cross-react or fail in IP. Captures the protein's whole RNA repertoire, not one RNA. Native RIP without crosslinking is prone to post-lysis reassociation artefacts (Mili and Steitz, RNA, 2004).

Method 3: Aptamer tags

An aptamer sequence (MS2 hairpin, PP7, S1, streptavidin-binding aptamer) is engineered into the RNA of interest, and a cognate protein or a resin captures it (Hogg and Collins, RNA, 2007; Srisawat and Engelke, RNA, 2001).

Strengths: High specificity; gentle elution is possible for some tags (biotin competition for the S1 aptamer).
Weaknesses: Requires modifying the RNA, so it does not work on endogenous unmodified transcripts. Developing a new aptamer for a new context adds weeks to months. The tag can alter RNA folding or localisation.

Method 4: Sequence-programmable phase-separation capture (LASSO)

Short DNA catcher strands complementary to the target are carried on a soluble polymer. Hybridisation to the target crosslinks the polymer network, which condenses into a pellet. Release is by strand displacement or a mild composition change under the same buffer conditions used for capture. No beads, no antibody, no boiling (Dynamic Matrices, Angewandte Chemie, 2025).

Strengths: Selectivity is by sequence, so off-target is lower than bead-charge binding; no solid surface, so background does not scale with capacity. Redesign for a new target is a new oligo set, days rather than weeks. Native release preserves RNA-protein complexes and protein activity.
Weaknesses: Newer, with a shorter validation record than the others. Requires a known target sequence; not applicable when the question is "what does this protein bind".

Side by side

Which to use

• You want the RNA partners of a protein: RIP or CLIP. Nothing else answers that question.
• You want the protein partners of a specific endogenous RNA, and you will identify them by mass spec after denaturing elution: biotin-streptavidin tiled probes (ChIRP) is the validated route.
• You want native complexes back, with activity intact, or you have many targets: sequence-programmable capture. See our native protein post.
• You can engineer the RNA and want a well-worn handle: aptamer tag.