Figure 8.

Response to successive stimuli of different signals with different strengths. At t=1 (time is in unit of k_R⁻¹), certain amount of serine ([L]₂=10⁻¹, 10, 10³ K₂^I for the three cases (columns) shown) is added to the mixed receptor system, followed by the addition of MeAsp ([L]₁=K₁^I) at t=11. (A–C) are activity adaptation curves from the MWC-type model, in which saturating amount of serine background, shown in (C), irreversibly inhibits the mixed receptor cluster and prohibits it from responding to further MeAsp addition (the poisoning effect). (D–F) Are activity adaptation curves from the local adaptation model, in which the system still respond to MeAsp partially even with large serine background. (G–I) Show the corresponding methylation level dynamics from the MWC model, and (J–L) show the methylation dynamics of the local adaptation model. (G–L) Clearly show that the local adaptation model limits the strength of methylation contamination, whereas severe methylation contamination exists in the MWC-type model. (M) Schematic illustration of methylation dynamics after adding saturating amount of serine under local adaptation model (upper row) and MWC-type model (bottom row). The blue color represents the Tar-related components and red color are the Tsr-related components. The water level inside each receptor represents activity of that particular receptor.