A statistical mechanics model for receptor clustering.

We introduce and study a simple lattice statistical mechanics modelfor the clustering of tumor necrosis factor receptor I (TNFR1).Our model explains clustering under over-expression of the cytoplasmicsignal transducer as well as the clustering induced via extracellularligand binding; also we explain why the loss of transducer leads to arapid break-up of the clusters. The basic mechanism at work is a first-order(cooperative) phase transition caused by the multimeric binding capability ofthe receptor-transducer complex. Using cooperativity of this type, the cellsare found to have an enhanced sensitivity and robustness. In general, ourmethod can be applied to other receptor-clustering related signaling system.