FIGURE 2.1. Functional cyclic nucleotide gated channels (CNG) and hyperpolarization-activated cyclic nucleotide-gated channels (HCN) are oligomers composed by four subunits.

FIGURE 2.1

Functional cyclic nucleotide gated channels (CNG) and hyperpolarization-activated cyclic nucleotide-gated channels (HCN) are oligomers composed by four subunits. The cyclic nucleotide binding domain (CNBD) is located close to the C-terminus of each subunit. (A) cAMP binding to the CNBD promotes opening of CNG but not HCN-channels at membrane potential > –40 mV. (B) cAMP binding to CNG-channels plus hyperpolarization of the cell induces a stronger inward cation current. HCN-channels are open during hyperpolarization, mid cAMP binding to the CNBD induces a faster opening of these channels. (C) Current-voltage relationship for CNG and HCN-channels in the presence (gray line) and absence (black line) of cAMP.

From: Chapter 2, Monitoring Receptor-Mediated Changes of Intracellular cAMP Level by Using Ion Channels and Fluorescent Proteins as Biosensors

Cover of Serotonin Receptors in Neurobiology
Serotonin Receptors in Neurobiology.
Chattopadhyay A, editor.
Boca Raton (FL): CRC Press/Taylor & Francis; 2007.
Copyright © 2007, Taylor & Francis Group, LLC.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.