Molecular mechanism for 3:1 subunit stoichiometry of rod cyclic nucleotide-gated ion channels

摘要: Molecular determinants of ion channel tetramerization are well characterized, but those involved in heteromeric assembly less clearly understood. The composition native channels is often precisely controlled. Cyclic nucleotide-gated (CNG) from rod photoreceptors exhibit a 3:1 stoichiometry CNGA1 and CNGB1 subunits that tunes the for their specialized role phototransduction. Here we show, using electrophysiology, fluorescence, biochemistry, X-ray crystallography, mechanism this controlled formation parallel 3-helix coiled-coil domain carboxy-terminal leucine zipper region subunits, constraining to contain three followed by preferential incorporation single subunit. Deletion relaxed constraint permitted multiple channel. crystal structures domains CNGA3 were similar, suggesting similar controls cone CNG channels.