Figure 1.

Schematic illustration of conformational fluctuations. (A) The MAX₂ homodimer adopts a basic-helix-loop-helix-leucine zipper (b/HLH/LZ) conformation preceded by a basic N-terminal domain (NTD) that houses the DNA binding epitope (35,36). (B) Scheme of two limiting cases: compact, closed DNA-bound state of MAX₂ (left) and open state (right) that features an increased distance between the two basic NTDs. The NTD samples a continuum of states with varying distances between the two subunits. The HLH motif serves as hinge between the LZ and basic domains. The different domains of MAX₂ are indicated on the right.