The function of KCND3 (potassium voltage-gated channel subfamily D member 3, ENSG00000171385) is as follows. Pore-forming (alpha) subunit of voltage-gated A-type potassium channels that mediates transmembrane potassium transport in excitable membranes, in brain and heart (PubMed:10200233, PubMed:17187064, PubMed:21349352, PubMed:22457051, PubMed:23280837, PubMed:23280838, PubMed:34997220, PubMed:9843794). In cardiomyocytes, may generate the transient outward potassium current I(To) (By similarity). In neurons, may conduct the transient subthreshold somatodendritic A-type potassium current (ISA) (By similarity). Kinetics properties are characterized by fast activation at subthreshold membrane potentials, rapid inactivation, and quick recovery from inactivation (PubMed:10200233, PubMed:17187064, PubMed:21349352, PubMed:22457051, PubMed:23280837, PubMed:23280838, PubMed:34997220, PubMed:9843794). Channel properties are modulated by interactions with regulatory subunits (PubMed:17187064, PubMed:34997220). Interaction with the regulatory subunits KCNIP1 or KCNIP2 modulates the channel gating kinetics namely channel activation and inactivation kinetics and rate of recovery from inactivation (PubMed:17187064, PubMed:34997220). Likewise, interaction with DPP6 modulates the channel gating kinetics namely channel activation and inactivation kinetics (PubMed:34997220). {ECO:0000250|UniProtKB:Q62897, ECO:0000269|PubMed:10200233, ECO:0000269|PubMed:17187064, ECO:0000269|PubMed:21349352, ECO:0000269|PubMed:22457051, ECO:0000269|PubMed:23280837, ECO:0000269|PubMed:23280838, ECO:0000269|PubMed:34997220, ECO:0000269|PubMed:9843794}.