A let-7 dsRNA precursor was mixed with embryonic lysate and UV crosslinked to proteins.

The wild-type double stranded let-7 miRNA precursor strongly favors binding to AGO1. However, removal of central base pairing mismatches shifts the preference to binding to AGO2.

Interaction in vitro; bait produced and labeled by in vitro transcription; bait derived from embryonic extract.

Interaction in vitro; bait synthesized and labeled in vitro; prey derived from wild-type embryo extract.

A synthetic double-stranded let-7 RNA preferentially binds AGO1. Changing the 5-prime nucleotide from U to C, removing the central base-pairing mismatches and decreasing the length from 22nt to 21nt shifts binding preference to AGO2.

Binding shown for let-7-5p isoform which corresponds to let-7-RA.

Source was S2 cell extract; bait produced from endogenous gene; prey produced from endogenous gene.