FIGURE 3.

RNP interactions. (A) N-terminal RRM of U1A prototype bound to RNA ligand. The RNP surfaces of UHM (cyan)–ULM (green) complexes, including (B) U2AF⁶⁵ UHM–SF1 ULM (PDB ID: 4FXW); (C) U2AF²³ UHM–U2AF⁵⁹ ULM (PDB ID: 4YH8); (D) SPF45 UHM–SF3b155 ULM5 (PDB ID 2PEH); and (E) CAPERα UHM–SF3b155 ULM5 (PDB ID: 4OZ1). The conserved aromatic residue at RNP1 position 5 typically is masked by a C-terminal extension (magenta) of the core UHM fold. The key residues at positions 2 of RNP2 and positions 3/5 of RNP1 are colored blue. Orange spheres represent zinc ions. Indigo, space-filling residues in C correspond to MDS-relevant mutations of the human homolog. Views are following an ∼120° rotation about the y-axis relative to Figure 2.