Enables cGMP binding activity and intracellular cGMP-activated cation channel activity. Involved in membrane depolarization; regulation of cytosolic calcium ion concentration; and spermatogenesis. Located in cytoplasm and terminal bouton. Part of intracellular cyclic nucleotide activated cation channel complex. Human ortholog(s) of this gene implicated in retinitis pigmentosa and retinitis pigmentosa 49. Orthologous to human CNGA1 (cyclic nucleotide gated channel subunit alpha 1). [provided by Alliance of Genome Resources, Apr 2022]