CUL4A interacting with DDB1 using its N-terminal region, which is partially removed by alternative splicing. The protein on the right is CUL4A. The region that is missing in the alternative isoforms is colored in red. The residues of CUL4A that interact with DDB1 and that are located in the alternatively spliced region are colored in orange, while the others in yellow. The other proteins present in the crystal are not included.