Figure 1.
The diagram shows two opposite subunits of the H C N 4 channel in the absence of cyclic adenosine monophosphate. The channel is divided into two main parts: the transmembrane part of the channel (T M P C) and the cytosolic part of the channel (C P C). The T M P C includes the voltage sensor domain (V S D), pore domain (P D), and selectivity filter (S F). The C P C includes the N terminus H C N domain (H C N D) and the C linker, which is formed by the shoulder and elbow, connecting the cyclic nucleotide binding domain (C N B D) to the P D. Transmembrane domains S 1 to S 6 are indicated on the grey subunit. The position of the membranes is indicated by grey lines.
General architecture and structural domains in HCN channels. Side view of two opposite subunits of HCN4 channel in absence of cAMP (PDB accession no. 7NMN). Structural domains are indicated as follow: the TMPC includes voltage sensor (VSD), PD, and SF. The CPC includes: the N terminus HCND and at the C terminus, the C-linker formed by shoulder and elbow, that connects the cyclic nucleotide-binding domain (CNBD) to the PD. Transmembrane domains S1–S6 are indicated on the gray subunit; the position of the membranes is indicated by gray lines.