. "Catalysis of the transmembrane transfer of a cation by a channel that opens when intracellular cyclic nucleotide has been bound by the channel complex or one of its constituent parts." . . . . "intracellular cyclic nucleotide activated cation channel activity" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .