Hyperpolarization activated cyclic nucleotide-gated potassium channel 4 (HCN4) is one of the subunits of hyperpolarization-activated cyclic nucleotide-gated channels, which have a role in synaptic transmission, dendritic integration, membrane and action potential. It is a heteromeric channel. HCN4 is highly expressed in rat embryonic hearts, specifically in the sinoatrial node.
