Anales RANF

S8-01 PERMEATION MECHANISMS OF LARGE CATIONS IN ATP- GATED P2X RECEPTORS T. Grutter CNRS, University of Strasbourg, France The permeability of large cations through the P2X pore has remained arguably the most controversial and complicated topic in P2X-related research, with the emergence of conflicting studies on the existence, mechanism and physiological relevance of a so- called “dilated” state. Due to the important role of several “dilating” P2X subtypes in numerous diseases, a clear and detailed understanding of this phenomenon represents a research priority. Recent advances, however, have challenged the existence of a progressive, ATP-induced pore dilation, by demonstrating that this phenomenon is an artefact of the method employed. In this talk, I will present how modern chemical optogenetics combined to single-channel recordings have provided new insights into the permeation of large cations. The physiological relevance of such a large cation- permeable pore will also be discussed.