Inferring single channel properties from the collective behavior of a cluster of channels: stochastic vs mean field models

SILVINA PONCE DAWSON

Workshop; Emergent behavior of biomolecular ensembles and networks; 2010

The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is a Ca2+ channel which provides a link between events at the plasma membrane and Ca2+ release from intracellular stores. Although there is a large body of experimental work on the IP3R, a comprehensive understanding of its kinetics is not complete. A variety of observations has led to the conclusion that the kinetics of the channel is very dependent on the environment. Thus, it is of interest to infer single channel properties from the observation of Ca2+ release through these channels in intact cells. The problem is that in most cells IP3s are clustered and is not always possible to resolve the intra-cluster dynamics. The combination of optical experiments and models provides a tool to tackle the problem of inferring single-channel properties from the observation of Ca2+ release through a cluster of channels. Many models, however, rely on a mean-field description of the cluster kinetics. In this talk I will describe how to combine models and experiments to infer single-channel properties from observations of Ca2+ release from clusters of channels discussing the advantages and limitations of using mean-field models to this end.