Ncs-1

Neuronal calcium sensor-1 (Ncs-1; also known as frequenin) transduces Ca²⁺ signals into change in function. It has no known catalytic function but regulates target proteins. Ncs-1 regulates neurotransmitter release and secretion. It modulates voltage-gated Ca²⁺ channels of the P/Q- and N-types. Ncs-1 is involved in synaptic plasticity, learning, and memory. It directly interacts with and activates phosphatidylinositol-4-OH kinase type III beta, 3'5'-cyclic nucleotide phosphodiesterase, nitric oxide synthase, and calcineurin. It inhibits downregulation of dopamine D2 receptors and regulates surface expression of A-type (Kv4) K⁺ channels. The protein sequence is identical in mouse, rat, human, and chicken.