The function of Ensembl gene identifier ENSG00000140015 (KCNH5, potassium voltage-gated channel subfamily H member 5) is as follows. Pore-forming (alpha) subunit of a voltage-gated delayed rectifier potassium channel that mediates outward-rectifying potassium currents which, on depolarization, reaches a steady-state level and do not inactivate (PubMed:11943152, PubMed:12135768, PubMed:24133262, PubMed:36928654). The kinetic is characterized by a slow activation time course and a small voltage dependence of the activation time constants, therefore, starts to open at more negative voltages (PubMed:11943152, PubMed:12135768). The activation kinetics depend on the prepulse potential and external divalent cation concentration (PubMed:11943152, PubMed:24133262). The time course of activation is biphasic with a fast and a slowly activating current component (PubMed:11943152, PubMed:12135768, PubMed:36928654). With negative prepulses, the current activation is delayed and slowed down several fold, whereas more positive prepulses speed up activation, therefore the activation rate depends on holding potential (PubMed:11943152, PubMed:12135768, PubMed:36928654). {ECO:0000269|PubMed:11943152, ECO:0000269|PubMed:12135768, ECO:0000269|PubMed:24133262, ECO:0000269|PubMed:36928654}.