Effect of nonspecific forces and finite receptor number on rate constants of ligand--cell bound-receptor interactions.
We develop a theory of ligand diffusion in the presence of a central potential toward or away from receptor patches that are uniformly distributed over a spherical cell. The current onto the receptors is reduced to less than that onto the sphere by a factor that is a nonlinear function of the number of free receptors, their size, and their potential energy. Similarly, under conditions defined by the theory, the dissociation rate from a receptor is reduced by the probability of rebinding to some other receptor on the same cell. This complicates the kinetic analysis, leading to the possibility of an occupancy-dependent dissociation rate, but has no effect on the interpretation of thermodynamic data.
D002462:Cell Membrane / Q000502:physiology*; D004058:Diffusion; D007700:Kinetics; D008024:Ligands; D008954:Models, Biological; D011955:Receptors, Drug / Q000502:physiology*
D008024:Ligands; D011955:Receptors, Drug