Summary of human mRBPs characterized by RNAcompete. The left panel shows, categorized by selected domain types, the number of RBPs for which RREs were characterized by RNAcompete (red) or remain to be studied (dark gray). RBD categories are RRM, RRM + other (combination of RRM with KH or zinc finger), KH and other RBDs selected in Ray et al. (zinc finger, PUF, CSD, YTH, S1 and SAM). The right panel shows the fraction of human mRBPs studied by RNAcompete. Of all known/putative mRBPs (n = 717; reviewed by Ascano et al. ), 20% were studied by RNAcompete (red, n = 146). Another 18% of mRBPs contain at least one or more of the selected RBDs but remain to be studied (dark gray, n = 127). Sixty-two percent of mRBPs contained RBDs (for example, DSRM, La, PWI, and so on) not studied by RNAcompete (light gray, n = 444).