Analysis of Small RNA-Guided Endonuclease Activity in Endogenous Piwi Protein Complexes from Mouse Testes

Small RNAs associate with members of the Argonaute family to function in gene regulation, transposon control, and creation of silent chromatin domains. In this partnership, small RNAs act as guides for the bound Argonaute and other associated proteins. Complementary base pairing of small RNAs to target nucleic acid molecules allow specificity for the small RNA-mediated functions. One key activity of some Argonaute protein family members is their small RNA-guided endonuclease activity called Slicer action. Here we describe a protocol that can be used to probe slicer activity in endogenous Piwi complexes isolated from mouse testes.