FC0012
Kinase inducible domain of CREB  -  KIX domain of CREB binding protein (CBP)

Biological function
Phosphorylation induces binding of the kinase-inducible domain (KID) of the cAMP response element-binding protein (CREB) to the KIX domain of CREB-binding protein (CBP).

Structural evidence
The 60 residue long KID domain has two low propensity helices in solution (120-129; 134-144), which are stabilized in the bound state. The KID structure in the complex is a helix-turn-helix centered around S133. Regions flanking the helices do not exhibit measurable resonance broadening, which could indicate contacts with KIX.

Biochemical evidence
K_D of the contructs with only the physically interacting residues is 3.1μM, using the whole KID is 0.7 μM. Flanking regions were shown not to increase helicity of the binding regions.

Mechanism category
tethering/ entropy modulation

Posttranslational modification
The binding is induced by the phosphorylation of S133, which is embedded in a motif: RRPS.

Significance
Transient interactions by fuzzy regions flanking the helix-turn-helix segment contribute to anchoring KID to KIX and increase binding entropy.