Fig. 1.

Schematic of selected assembly states for PR-A–PRE₂ interactions. (A) Dimer binding pathway. Circles represent hormone-bound PR-A structure, and squares represent PR-A solution dimers (k_di) or PR-A bound to the PRE₂ promoter (k₂). (B) Monomer binding pathway. Successive binding at an individual response element (k₁) is accompanied by an intrasite cooperative interaction (k_c1) represented by a transition from a filled circle to a filled square. Binding at multiple response elements is accompanied by an intersite cooperative interaction (k_c2). Arrow refers to the direction of transcriptional start site.