KCNE3 (also known as MinK-related peptide 3 or MiRP2) is a potassium channel regulatory subunit that modulates the function of voltage-gated potassium channels, particularly [KCNQ1](/proteins/kcnq1-protein) (also known as Kv7.1). The protein plays critical roles in regulating neuronal excitability, cardiac repolarization, and epithelial transport. KCNE3 is encoded by the [KCNE3](/genes/kcne3) gene located on chromosome 11.
KCNE3 is a member of the KCNE family (KCNE1-5), which are small single-pass membrane proteins that assemble with voltage-gated potassium channel α-subunits to form functional channels with diverse properties. Unlike KCNE1, which slows activation, KCNE3 accelerates activation and shifts the voltage dependence of channel opening.
Structure
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KCNE3 Protein (MinK-Related Peptide 3)
Overview
KCNE3 (also known as MinK-related peptide 3 or MiRP2) is a potassium channel regulatory subunit that modulates the function of voltage-gated potassium channels, particularly [KCNQ1](/proteins/kcnq1-protein) (also known as Kv7.1). The protein plays critical roles in regulating neuronal excitability, cardiac repolarization, and epithelial transport. KCNE3 is encoded by the [KCNE3](/genes/kcne3) gene located on chromosome 11.
KCNE3 is a member of the KCNE family (KCNE1-5), which are small single-pass membrane proteins that assemble with voltage-gated potassium channel α-subunits to form functional channels with diverse properties. Unlike KCNE1, which slows activation, KCNE3 accelerates activation and shifts the voltage dependence of channel opening.
KCNE3 contains a single transmembrane α-helix that anchors the protein in the plasma membrane. The extracellular N-terminal domain and intracellular C-terminal tail interact with the S4-S5 linker and C-terminal domain of KCNQ1 channels to modulate their gating properties. The protein forms disulfide bonds with channel β-subunits and undergoes post-translational modifications including glycosylation.
Normal Physiological Function
Potassium Channel Modulation
KCNE3 primarily assembles with [KCNQ1](/proteins/kcnq1-protein) to form channels with distinct properties compared to KCNE1-containing channels. Key functions include:
KCNQ1/KCNE3 channels: Generate slowly activating, non-inactivating currents that contribute to the M-current, a key regulator of neuronal excitability
Voltage dependence: Shifts activation to more negative potentials, making channels more responsive at resting membrane potentials
Kinetic properties: Accelerates activation kinetics compared to homomeric KCNQ1 channels
Tissue Distribution
KCNE3 is expressed in:
Brain: Hippocampus, cortex, and basal ganglia — regions affected in Alzheimer's and Parkinson's disease
Heart: Cardiac ventricles where it contributes to repolarization
Inner ear: Hair cells involved in auditory transduction
Epithelial tissues: Kidney and intestine
Neuronal Function
In neurons, KCNQ1/KCNE3 channels regulate:
Resting membrane potential stability
Action potential threshold
Spike frequency adaptation
Synaptic integration
These channels are critical for preventing hyperexcitability and maintaining proper neuronal signaling.
Role in Neurodegenerative Diseases
Alzheimer's Disease
Potassium channel dysfunction is increasingly recognized in Alzheimer's disease pathophysiology: