KCNMB1 (Potassium Calcium-Activated Channel Regulatory Subunit Beta 1) encodes the beta-1 subunit of the large-conductance calcium-activated potassium (BK) channel, also known as MaxiK or Slo1. BK channels are widely expressed in [neurons](/entities/neurons) where they regulate neuronal excitability, action potential duration, and neurotransmitter release.
Channel Regulation
The KCNMB1 protein modulates BK channel function by:
Increasing channel opening probability in response to intracellular calcium
Enhancing channel sensitivity to voltage changes
Facilitating rapid repolarization and limiting excitotoxicity
Modulating neurotransmitter release at synaptic terminals
Neuronal Expression
KCNMB1 is expressed in various brain regions including:
KCNMB1 variants have been associated with epilepsy susceptibility. BK channel dysfunction can lead to neuronal hyperexcitability and seizure generation. Studies have identified rare missense variants in epilepsy patients affecting channel gating properties.
Intellectual Disability
Loss-of-function variants in KCNMB1 have been linked to neurodevelopmental disorders including intellectual disability, possibly through impaired synaptic plasticity and neuronal connectivity.
Ataxia
KCNMB1 mutations may contribute to cerebellar ataxia through disrupted Purkinje cell function and impaired cerebellar circuit signaling.
Cancer Associations
KCNMB1 is overexpressed in several cancers and may promote tumor progression through effects on cell proliferation and migration.