Flag-biotin Clip-seq

Ultraviolet irradiation is the capture-enabling step: it covalently links the tagged RNA-binding protein to RNA that is nearby at the time of exposure. Because the protein-RNA association is chemically fixed, the linked material can proceed through affinity purification rather than relying only on a noncovalent interaction. This provides the physical basis for recovering associated RNA.

FLAG and biotin serve as complementary affinity handles on the tagged protein. Their presence allows the crosslinked protein-RNA complexes to be selectively purified from other cellular material before the RNA is processed. These handles focus the experiment on RNA associated with the designated RNA-binding protein, strengthening the connection between recovered sequences and protein occupancy.

Sequencing provides the readout used to locate binding sites across the associated transcripts. After purification, the RNA is converted into sequencing libraries, and the resulting sequences are analyzed to identify where binding occurs. The workflow therefore converts biochemical enrichment of RNA-protein complexes into an interaction map that shows the positions of RNA-binding protein association.

At a high level, the workflow moves from crosslinking to selective recovery and then to readout. Ultraviolet irradiation first fixes protein-RNA contacts, while FLAG and biotin affinity handles support purification of the complexes. The associated RNA is then converted into sequencing libraries, and analysis of those libraries identifies protein-associated binding sites for interpretation.

Flag-biotin CLIP-seq can identify which transcripts are associated with a particular RNA-binding protein, rather than inferring regulation only from changes in RNA abundance. The resulting interaction map can be examined alongside transcript processing, stability, localization, or translation. This helps researchers connect binding events with specific post-transcriptional regulatory mechanisms.

In genetics, the maps help examine how RNA-protein interactions contribute to phenotypes. If binding patterns change in a developmental condition or disease context, the data can provide a mechanistic link between altered post-transcriptional regulation and the phenotype. They can also help investigate whether disease-associated genetic variation affects regulatory interactions involving the RNA-binding protein.