Constitutively active mutants of 5‐HT 4 receptors are they in unique active states?

Sylvie Claeysen (1) , Michèle Sebben (1) , Carine Becamel (1) , Marie-Laure Parmentier (1) , Aline Dumuis (1) , Joël Bockaert (1)

1 CCIPE - Centre CNRS-INSERM de Pharmacologie Endocrinologie

Somatic mutations leading to constitutively active G-protein coupled receptors (GPCRs) are responsible for certain human diseases. A consistent structural description of the molecular change underlying the conversion of GPCRs from an inactive R state to an active R* state is lacking. Here, we show that a series of constitutively active 5-HT4 receptors (mutated or truncated in the C-terminal and the third intracellular loop) were characterized by an increase in their denaturation rate at 55°C. The thermal denaturation kinetics were monophasic, suggesting that we were measuring mainly the denaturation rate of R*. Analysis of these kinetics revealed that constitutively active C-terminal domain mutants, were due to a change in the J constant governing the R/R* equilibrium. However, the constitutive activity of the receptor mutated within the third intracellular loop was the result of both a change in the allosteric J constant and a change in the R* conformation.

Domaines: Biochimie, Biologie Moléculaire

Sylvie Claeysen, Michèle Sebben, Carine Becamel, Marie-Laure Parmentier, Aline Dumuis, et al.. Constitutively active mutants of 5‐HT 4 receptors are they in unique active states?. EMBO Reports, 2001, 2 (1), pp.61-67. ⟨10.1093/embo-reports/kve003⟩. ⟨hal-02486964⟩