Characterization of multiple binding sites on microtubule associated protein 2c recognized by dimeric and monomeric 14‐3‐3ζ

Microtubule associated protein 2 (MAP2) interacts with the regulatory protein 14‐3‐3ζ in a cAMP‐dependent protein kinase (PKA) phosphorylation dependent manner. Using selective phosphorylation, calorimetry, nuclear magnetic resonance, chemical crosslinking, and X‐ray crystallography, we characterized interactions of 14‐3‐3ζ with various binding regions of MAP2c. Although PKA phosphorylation increases the affinity of MAP2c for 14‐3‐3ζ in the proline rich region and C‐terminal domain, unphosphorylated MAP2c also binds the dimeric 14‐3‐3ζ via its microtubule binding domain and variable central domain. Monomerization of 14‐3‐3ζ leads to the loss of affinity for the unphosphorylated residues. In neuroblastoma cell extract, MAP2c is heavily phosphorylated by PKA and the proline kinase ERK2. Although 14‐3‐3ζ dimer or monomer do not interact with the residues phosphorylated by ERK2, ERK2 phosphorylation of MAP2c in the C‐terminal domain reduces the binding of MAP2c to both oligomeric variants of 14‐3‐3ζ.