| Type: | Family | Name: | Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 |
| Description: | This entry represents HCN4, which belongs to the hyperpolarisation-activated cyclic nucleotide-gated (HCN) channel family. It is the major HCN channel isoform detected in heart and in the atrioventricular node []. It is required for the formation of adult pacemaker cells during embryonic heart development and for the cAMP-dependent up-regulation of embryonic heart rate. It is also strongly expressed in some parts of the brain, such the thalamic nuclei and the mitral cell layer of the olfactory bulb [, ].The hyperpolarisation-activated cation current (termed I(f), I(h), or I(q)) plays a key role in the initiation and modulation of cardiac and neuronal pacemaker depolarisations. This current is carried by both K+ and Na+ through I(h) or I(f) channels, such as members of the hyperpolarisation-activated cyclic nucleotide-gated (HCN) family. HCN channels belong to the superfamily of voltage-gated pore loop channels. The voltage-dependent opening ofthe HCN channels is directly regulated by the binding of cAMP. In vertebrates, the HCN channel family comprises four members (HCN1-4) []. Whereas HCN3 seems to be specifically expressed in neurons, the other three channels (HCN1, 2, and 4) have been detected in both heart and brain [, ]. HCN channels contain six membrane-spanning helices (S1-S6), including a positively charged voltage-sensing S4 segment and an ion-conducting pore between S5 and S6. In the C terminus the channels carry a cyclic nucleotide-binding domain (CNBD) []. Binding of cAMP to the CNBD speeds up channel opening and shifts the voltage-dependence of activation to more positive voltages []. HCN channels exhibit weak selectivity for potassium over sodium ions. | Short Name: | HCN4 |
| GO Term | Gene Name |
|---|---|
| GO:0005249 | IPR030173 |
| GO:0030552 | IPR030173 |
| GO:0002027 | IPR030173 |
| GO:0006813 | IPR030173 |
| GO:0006814 | IPR030173 |
| GO:0016021 | IPR030173 |
| GO Term | Gene Name |
|---|---|
| GO:0005249 | IPR030173 |
| GO:0030552 | IPR030173 |
| GO:0002027 | IPR030173 |
| GO:0006813 | IPR030173 |
| GO:0006814 | IPR030173 |
| GO:0016021 | IPR030173 |
| DB identifier | Type | Name |
|---|---|---|
| IPR003938 | Family | Potassium channel, voltage-dependent, EAG/ELK/ERG |
