Modelling the activation of G-protein coupled receptors by a single drug.

In this paper, the most popular proposed mechanism for activation of G-protein coupled receptors (GPCRs)--the shuttling mechanism--is modelled mathematically. An asymptotic analysis of this model clarifies the dynamics of the system in the presence of a drug, in particular identifying which reactions dominate during the different timescales. The modelling also reveals challenging behaviour in the form of a peak response. This new mechanism gives simple explanations for complex, possibly misunderstood, behaviour.