PDBsum entry 5khj

Transport protein

PDB id: 5khj

Contents

Protein chains

199 a.a.

Ligands

6SY ×2

Waters ×314

References listed in PDB file

Key reference

• Title: Cyclic purine and pyrimidine nucleotides bind to the hcn2 ion channel and variably promote c-Terminal domain interactions and opening.
• Authors: L.C.T.Ng, I.Putrenko, V.Baronas, F.Van petegem, E.A.Accili.
• Ref.: Structure, 2016, 24, 1629-1642.
• PubMed id: 27568927

Abstract

Cyclic AMP is thought to facilitate the opening of the HCN2 channel by binding to a C-terminal domain and promoting or inhibiting interactions between subunits. Here, we correlated the ability of cyclic nucleotides to promote interactions of isolated HCN2 C-terminal domains in solution with their ability to facilitate channel opening. Cyclic IMP, a cyclic purine nucleotide, and cCMP, a cyclic pyrimidine nucleotide, bind to a C-terminal domain containing the cyclic nucleotide-binding domain but, in contrast to other cyclic nucleotides examined, fail to promote its oligomerization, and produce only modest facilitation of opening of the full-length channel. Comparisons between ligand bound structures identify a region between the sixth and seventh β strands and the distal C helix as important for facilitation and tight binding. We propose that promotion of interactions between the C-terminal domains by a given ligand contribute to its ability to facilitate opening of the full-length channel.