Single ligand-receptor interaction

Experiments with both fibroblasts [104] and FRTL-5 cells [105] indicate that a single ligand, presumably interacting with a single receptor, may activate in the same cell both a PTX-sensitive Gp a and a PTX-insensitive Gplc. 

The mathematics of ligand-receptor interactions are beyond the scope of the cvurent article. Therefore, only important summary equations describing the bimolecular interaction of L with a single class of receptor are given below. These equations are analogous to the fundamental description of enzyme-substrate interactions first proposed by Michaelis and Menten, with the exception that L replaces the term for substrate, R replaces the enzyme, and LR substitutes for the enzyme-substrate complex. In binding reactions there is no term for product, since the binding of L to R does not result in the alteration of L. 

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