Proteins are Not Recruited: A Plea for Better Diction

Nearly all biological processes proceed or are controlled by protein-protein or protein-ligand binding reactions. Using anthropomorphic language to describe these interactions conveys an incorrect physical description of these processes while simultaneously minimizing the importance of the thermodynamics underpinning the associated interactions. Indeed, we should never say that proteins are recruited to binding partners or binding sites since this implies both a non- existent level of communication within biological systems and a non-existent process by which proteins or binding sites actively seek other proteins. Both of these fictions hinder our ability to determine quantitatively or qualitatively distinct biophysical descriptions of the associated systems. Here we present examples of how interactions typically described as protein recruitment can be more accurately and often more simply described as variations within binding equilibria. We argue that this approach is better for describing protein-protein and protein-ligand binding, even when the objective is only a qualitative description, especially for discussions with students in courses and research groups as it provides testable models for these interaction