Weighing up the Selenocysteome Uncovers New Sec-rets.

Challenging the paradigm of SECIS-dependent selenoprotein translation, in this issue of Cell Chemical BiologyGuo et al. (2018) introduce a new selenoprotein profiling platform with which they identify novel selenoproteins apparently lacking SECIS. With increased interest in covalent targeting of reactive Sec residues in drug discovery, their method adds a valuable contribution toward expanding the druggable human proteome.