Baltz, A.G. et al. Mol. Cell 46, 674–690 (2012).

Castello, A. et al. Cell 149, 1393–1406 (2012).

To understand how RNA exerts its many functions, one needs to understand which proteins it interacts with. The study of RNA-binding proteins (RBPs) has occupied scientists during the last two decades, and the more recent combination of cross-linking and immunoprecipitation (CLIP) with high-throughput sequencing has provided a better understanding of RNA-binding motifs. Two independent research efforts now substantially add to the catalog of known RBPs in human cells. By pairing methods similar to photoactivatable ribonucleoside-enhanced CLIP with quantitative proteomics, Baltz et al. identified around 250 new RBPs in human embryonic kidney cells and derived protein occupancy profiles by high-throughput sequencing, and Castello et al. added more than 300 new RBPs from HeLa cells to the existing repertoire.