Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume.

KCNE5 encodes a membrane protein, KCNE5 (originally named KCNE1-L) that has sequence similarity to the KCNE1 gene product, a member of the potassium channel, voltage-gated, isk-related subfamily.

[5] Human KCNE5 transcripts are most highly expressed in cardiac and skeletal muscle, spinal cord and brain, and it is also detectable in placenta.

[5][13] In mice, Kcne5 transcript was detected in embryonic cranial nerve migrating crest cells, ganglia, somites and myoepicaridal layer.

Atrial fibrillation is the most common chronic cardiac arrhythmia, affecting 2-3 million in the United States alone, predominantly in the aging population.

In contrast, a polymorphism in KCNE5 encoding a P33S substitution was found to be less common in atrial fibrillation patients than in control subjects,[14] although these findings were at odds with those of other studies.