Transients in the frequency response of the EGFR and GPCR systems. (A&C) The rise time, t
99 taken for the transient term in frequency response to decay by 99% was normalized with the input wavelength λ and is plotted as a function of frequency for the EGFR (A) and GPCR (C) systems. The normalized rise time quantifies the number of input pulses beyond which the steady-state response is reached. The black dotted lines in panels A and C are drawn at a normalized rise time value of 1. (B&D) The input wavelength, λ
for which the response reaches steady-state in a single input pulse (t
99/λ = 1) is plotted as function of the extent of downregulation, D for the EGFR (B) and the desensitization rate k
for the GPCR (D). For input wavelengths λ > λ
the system responds with virtually no transient.