1. Epidermal growth factor receptor binding is not a simple one-step process*
- Author
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Mayo, K H, Nunez, M, Burke, C, Starbuck, C, Lauffenburger, D, and Savage, C R
- Abstract
The binding kinetics of 125I-labeled mouse epidermal growth factor (EGF) to receptors on human fibroblast cells in monolayer culture were measured at 4 ° C. Initial binding rates as a function of hormone concentration allowed estimation of simple two-state on-off rate constants of 1.2 × 106M−1s−1and 4.9 × 10−3s−1, respectively. These two-state parameters gave inadequate computer fits to long term kinetic and equilibrium-binding data, suggesting that an additional process(es) was occurring. Nonlinear equilibrium Scatchard plots and transient “pseudo-Scatchard” plots taken at pre-equilibrium times support the idea that at least one other process is occurring during receptor binding. 125I-EGF-receptor dissociation kinetic plots were biphasic, yielding rate constants of 1.5 × 10−2s−1and 5.6 × 10−5s−1with the ratio of the two components changing with the time of initial incubation with 125I-EGF. Application of a ternary complex model which assumed complexation of the bound receptor with a cell surface interaction molecule gave satisfactory fits to all data.
- Published
- 1989
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