Calcium:manganese antiporter of the plasma membrane mediating the efflux of intracellular manganese coupled to an active extracellular calcium exchange. Required for intracellular manganese homeostasis, an essential cation for the function of several enzymes, including some crucially important for the metabolism of neurotransmitters and other neuronal metabolic pathways. Manganese can also be cytotoxic and induce oxidative stress, mitochondrial dysfunction and apoptosis. Could also have an intracellular zinc ion transporter activity, directly regulating intracellular zinc ion homeostasis and more indirectly various signaling pathway and biological processes.