Visual signal transduction is mediated by a G-protein coupled cascade using cGMP as second messenger. This protein can be activated by cGMP which leads to an opening of the cation channel and thereby causing a depolarization of rod photoreceptors. Essential for the generation of light-evoked electrical responses in the red-, green- and blue sensitive cones (By similarity). Induced a flickering channel gating, weakened the outward rectification in the presence of extracellular calcium, increased sensitivity for L-cis diltiazem and enhanced the cAMP efficacy of the channel when coexpressed with CNGA3. Tetramer formed of three CNGA3 and one CNGB3 modulatory subunits. Small subset of retinal photoreceptor cells and testis. Belongs to the cyclic nucleotide-gated cation channel (TC 1.A.1.5) family. CNGB3 subfamily.