(only non-hydrogen atoms are shown) and Nrd1 CID is shown as a grey ribbon model. Nrd1 CID residues that form hydrophobic contacts and putative hydrogen bonds to Sen1 NIM peptide are shown in magenta sticks. B) Electrostatic surface representation of Nrd1 CID (electropositive in blue; electronegative in red; neutral in white) with the Sen1 NIM peptide (represented in yellow sticks; only non-hydrogen atoms are shown). The upstream electronegative stretch of Sen1 NIM interacts with an electropositive pocket of Nrd1 CID, while the C-terminal part of the peptide adopts an extended conformation that docks in a hydrophobic pocket of Nrd1 CID. C) Superposition of Nrd1 CID-Sen1 NIM (yellow) and Nrd1 CID-Trf4 NIM (magenta) complexes, displaying only peptide ribbons on the surface of Nrd1 CID. The comparison highlights the extended and β-turn conformations of Sen1 NIM and Trf4 NIM, respectively. 