Figure 5. Analytical solution of ERK phosphorylation by MEK under the condition of macromolecular crowding.

The fractions of np-ERK (blue), pY-ERK (green) and pTpY-ERK (red) were calculated according to Eq. 21–23. Experimental data are the same in Figure 2A and 2B (Exp. #2 in Supplementary Data set). The parameters of the numerical simulations were as follows: r_MEK = 45^1/3, r_ERK = 42^1/3, r_MEK-ERK = 87^1/3, r_croder = 6^1/3, g = 0.11, θ = 2.26, r_reac = 10 nm, D_water = 10 μm²/sec, τ_rel = 0.020 msec.