A. Protein sequence alignment of the HEAT8 hairpin and TAF1-TAND1, and the HEAT19 loop and TAF1-TAND2 (numbers represent amino acid positions). α-helices were assigned based on crystal structures and are depicted as blue cylinders. The Phe57 anchor residue of TAND2 is indicated 24[]. Black color highlights amino acid identity and gray shading indicates amino acids with similar properties. 