The function of KCNE4 (potassium voltage-gated channel subfamily E regulatory subunit 4, ENSG00000152049) is as follows. Ancillary protein that functions as a regulatory subunit of the voltage-gated potassium (Kv) channel complex composed of pore- forming and potassium-conducting alpha subunits and of regulatory beta subunits. KCNE4 beta subunit modulates the gating kinetics and enhances stability of the channel complex (PubMed:12096056, PubMed:19687231, PubMed:20533308, PubMed:27162025). Associates with KCNQ1/KVLTQ1 alpha subunit to inhibit potassium currents (PubMed:12096056, PubMed:19687231, PubMed:20533308, PubMed:27162025). {ECO:0000269|PubMed:12096056, ECO:0000269|PubMed:19687231, ECO:0000269|PubMed:20533308, ECO:0000269|PubMed:27162025}. [Isoform 2]: May inhibit KCNQ4-mediated potassium currents. .