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:10880439, PubMed:11943152, PubMed:22732247, PubMed:25420144, PubMed:25556795, PubMed:25915598, PubMed:27005320, PubMed:27325704, PubMed:27618660, PubMed:30149017, PubMed:9738473). The activation kinetics depend on the prepulse potential and external divalent cation concentration (PubMed:11943152). With negative prepulses, the current activation is delayed and slowed down several fold, whereas more positive prepulses speed up activation (PubMed:11943152). The time course of activation is biphasic with a fast and a slowly activating current component (PubMed:11943152). Activates at more positive membrane potentials and exhibit a steeper activation curve (PubMed:11943152). Channel properties are modulated by subunit assembly (PubMed:11943152). Mediates IK(NI) current in myoblasts (PubMed:9738473). Involved in the regulation of cell proliferation and differentiation, in particular adipogenic and osteogenic differentiation in bone marrow-derived mesenchymal stem cells (MSCs) (PubMed:23881642). {ECO:0000269|PubMed:10880439, ECO:0000269|PubMed:11943152, ECO:0000269|PubMed:22732247, ECO:0000269|PubMed:23881642, ECO:0000269|PubMed:25420144, ECO:0000269|PubMed:25556795, ECO:0000269|PubMed:25915598, ECO:0000269|PubMed:27005320, ECO:0000269|PubMed:27325704, ECO:0000269|PubMed:27618660, ECO:0000269|PubMed:30149017, ECO:0000269|PubMed:9738473}. This is the function of Ensembl gene identifier ENSG00000143473 (KCNH1, potassium voltage-gated channel subfamily H member 1).