Extracellular, surface, and internalized response to step changes in ligand input rate.

<p>Concentration responses of L, RS, LRS, and LRI to step changes in the ligand input rate. Two inputs of 10 s duration separated by a recovery phase of 40 s were considered. In both inputs ligand enters the system at a constant rate of 1 nM/s. , , . Panel A: ligand response computed at the outer region of the extracellular medium (, curve a) and at the interface with the cell surface (, curve b). Panel B: concentration-time profiles of empty (X = RS) and occupied (X = LRS) cell surface receptors obtained at . Panel C: concentration-time profiles of internalized ligand-receptor complexes computed at the surface of the cell (, curve a) and in the center of the cell (, curve b). Other conditions as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021786#pone-0021786-g003" target="_blank">Fig.3</a>.