Our dynamic light scattering investigation of a polyelectrolyte ELP reports a novel influence of common biological buffer molecules on ELP LCST behavior. Our findings are consistent with recent discussions of intrinsically disordered regions as inherent sensors of physicochemical changes. We hope that further systematic and wide-ranging investigations will follow. Key areas for exploration include the effect of co-solute molecules on rates of ELP assembly, the kinetics and hysteresis of the phase transition, how the sensitivity of an ELP to a given co-solute is encoded in its sequence, the influence of molecular crowding, and the thermodynamics of the various competing interactions present in the system. A deeper understanding of how co-solutes modulate ELP LCST behavior will facilitate their use as stimuli-responsive polymeric materials in various and dynamic environments and will be especially important to fully realize their promise in sensing applications.