Enables identical protein binding activity; large conductance calcium-activated potassium channel activity; and ligand-gated ion channel activity involved in regulation of presynaptic membrane potential. Involved in several processes, including negative regulation of small intestine smooth muscle contraction; positive regulation of neuron apoptotic process; and response to estrogen. Located in several cellular components, including external side of plasma membrane; neuronal cell body; and presynaptic active zone membrane. Part of protein-containing complex. Is active in glutamatergic synapse. Is integral component of presynaptic active zone membrane. Colocalizes with mitochondrion. Human ortholog(s) of this gene implicated in Alzheimer's disease and idiopathic generalized epilepsy. Orthologous to human KCNMA1 (potassium calcium-activated channel subfamily M alpha 1). [provided by Alliance of Genome Resources, Apr 2022]