Figure 4

Validation of preferential affinity. (a) GO molecular function term significance in the various sets of proteins inferred to bind preferentially one or several subtypes of nucleic acids. We observe the clear separation between molecular functions enriched in inferred DNA- and RNA-binding proteins. Color log-scale: red = P < 1E-15, light yellow = P < 0.01, gray = P ≥ 0.01. (b) Examples of affinity preferences of selected NABPs represented by P-values in the statistical analysis (table on left) and western blots in the experimental validation (right). We note the strong agreement between preferred versus non-preferred affinities in the statistics and the blots. (C20orf72 was purified with a Myc tag in HEK293 cells instead of a specific antibody in HepG2 cells.) (c) Methylation specificity usually correlates with CG specificity, but UHRF1 and YB-1 were specific to mCG only in the statistical analysis (see reported P-values in the table on the left). Experimental validation confirmed their specificity (right); AIM2 was used as a DNA-binding non-specific control.