Figure 6. Mode of Munc13–1/RIM2α ZF Domain Binding.

(A) Ribbon diagram of the complex formed by RIM2α _82–142 (blue) and monomer A of Munc13–1 _3–150(K32E) (orange), with the zinc atoms shown as yellow spheres. The β-strands are labeled with numbers, and the α-helix at the C-terminus of the ZF domain is labeled a2. The N- and C-termini are indicated with N and C, respectively.

(B) and (C) Space-filling models of the same complex shown in the same orientation as (A) and after rotating approximately 180° around the horizontal axis (C).

(D) and (E) Interfaces of the RIM2α ZF domain with the Munc13–1 C-terminal α-helix (D) and C ₂A domain (E). The side chains from residues involved in intermolecular contacts and the Cα carbons of the same residues are shown as stick models, with oxygen atoms in red, nitrogen atoms in blue, and sulfur atoms in purple; Cα carbons are shown with the same color as the ribbon, and other carbons are shown in gray for RIM2α _82–142 and in yellow for Munc13–1 _3–150(K32E). Backbone carbonyl groups involved in selected hydrogen bonds (dotted lines) are also shown as stick models. For simplicity, other hydrogen bonds are not shown.