Cyclic-nucleotide-gated channels ... might be the length and/or secondary structure of the S4–S5 linker. Reciprocal-space refinement of the entire model was carried out using Phenix 56.

However, the 3D structure of ABCC4 and the molecular mechanism ... form ABCC4 adopts an inward-facing conformation with the two nucleotide-binding domains (NBDs) separated from each other.