3'-Biotin-tagged microRNA-27 does not associate with Argonaute proteins in cells.

Synthetic 3'-biotin-tagged microRNAs (miRNAs) have often been used to select interacting messenger RNA (mRNA) and noncoding RNA (ncRNA) targets. Here, we examined the extent of association of 3'-end biotinylated miR-27 with Argonaute (Ago) proteins in transfected human cells using a coimmunoprecipitation assay followed by Northern blot analysis. We report that biotinylated miR-27 does not efficiently associate with Ago compared to unmodified miR-27. These results suggest that 3'-end biotin-modified miRNAs are questionable monitors of miRNA function in cells.