Discovery experiment identifying proteins closely associated with miRNAs comprising the GDCGG motif. (A) Workflow of miRNA pull-down experiments in lysates of HEK293 cells and sequences of 5′-biotinylated miRNAs used. (B) Representative SDS-PAGE of a typical miRNA pull-down experiment followed by staining with Coomassie brilliant blue. (C) List of the 28 candidate proteins (official gene symbols) putatively associated with GDCGG miRNAs (see main text for statistical details). The graph shows the fold change calculated from the most stringent comparison [miR-638wt versus miR-638mut1; n = 3–4; bars indicate mean ± standard error of the mean (SEM)]. (D and E) Results of the top two candidate proteins FXR1 and FXR2 (D), as well as of the highest ranked protein that missed our stringent selection criteria, MRPS26 (E), in all three statistical comparisons performed (miR-638wt versus miR-638mut1, miR-638wt versus miR-638mut2 and miR-4745-5p versus Cel-miR-39-3p; n = 3–4; bars indicate mean ± SEM. Corrected P-values: *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001; uncorrected P-values: ^#P ≤ 0.05, ^##P ≤ 0.01.