Fig. 8: SURF2 is able to directly interact with both RPL5 and RPL11 and competes for their binding with MDM2 in vivo.

a Extracts from U2OS cells that overexpress SURF2 (OE SURF2-Flag) or not (control) and treated by actinomycin D (ACTD) are used to perform IPs using beads only, beads coupled to anti-SURF2 or beads coupled to anti-MDM2. After washes, the remaining proteins are resuspended in loading dye and analyzed by western blots using the indicated antibodies. Red arrows indicate unspecify bands (IgG) (n = 2). b Same as in (a) but using northern blot to test for RNA binding. Probes against 5S and 5.8S were used (n = 3). c Quantification of northern-blot signals to test for specific enrichment of RNA species (n = 3). Use of an unpaired two-tailed t test for statistical tests. Data are presented as mean values +/− SD, and significant differences are indicated by stars as follows p-value < 0.05*; 0.01** 0.001*** and 0.0001****) or with the precise p-value on the graph (p). d Secondary structure of SURF2 and MDM2 proteins. Functional domains are indicated. SURF2 3D structure modelization by Alphafold software is represented. e GST-pulldown assays. Extracts of BL21 that overexpress recombinant SURF2-HIS were mixed with extracts that overexpress either GST alone, GST-RPL5, or GST-RPL11. Proteins specifically retained on glutathione-sepharose beads were analyzed both by Coomassie staining and western-blot analysis (WB). 10% of the extracts were used for inputs (n = 2). f Same experiments as in (e) but replacing extract with SURF2-HIS by extracts that overexpress structural domain of SURF2 (SURF2-SD-HIS) as prey. Proteins specifically retained on glutathione-sepharose beads were analyzed both by western blots with indicated antibodies (n = 2). Source data are provided as a Source Data file.