FIG. 4.

Site-specific phosphorylation induces tertiary structure in ID AF1 domain. (A to F) Fluorescence emission spectra of AF1 and AF1-S211A with or without p38 MAPK and AF1-S211E recorded at a 278-nm (A to C) or 295-nm (D to F) excitation wavelength. AF1, unphosphorylated AF1; AF1-P, phosphorylated; AF1-A, AF1S211A mutant; AF1-E, AF1S211E mutant. Each spectrum was recorded in the emission wavelength range of 300 to 400 nm, and the result of one representative spectrum of at least three independent experiments is presented, corrected for the contribution of the buffer, and smoothed.