SPIN1 (Spindlin 1) is a chromatin reader protein. It recognizes trimethylated histone H3 lysine 4 (H3K4me3) through the protein-protein interaction at the defined “aromatic cage” in Tudor domain II. The interaction between asymmetrically dimethylated histone H3 arginine 8 (H3R8me2a) and Tudor domain I further increases the affinity. On the...