Extended Data Fig. 3: Subunit ___domain structures and their inter-molecular interactions.

a–b, Domain arrangements of Rco1_L and Sin3 in the Rpd3S complex. c, Interactions between Sin3 HID C-module (ribbon model) and Rpd3 (electrostatic surface). d, Interactions between Sin3 HID C-module (electrostatic surface) and Rco1_L N-terminal ___domain (ribbon model). Interacting residues of Rco1_L are indicated as sticks. e, Superimposition of Sin3 HID C-module structure with the previously published Sin3A HID structure (PDB code 2N2H)¹⁷. f, Detailed interactions between Sin3 HID N-module and Eaf3 MRG. Residues involved in interactions are illustrated as sticks. Yellow dashed lines represent polar interactions. g, Detailed interactions between Rpd3 and Sin3 HID N-module. Residues mediating subunit contacts are represented as sticks. h, Superimposition of Sin3 PAH3 and Sin3A PAH3 (PDB code 2LD7)¹⁸. i, Interactions between Sin3 and Rco1_L PHD2. Highlighted as sticks are residues involved in the interactions between the two proteins. Yellow dashed lines denote hydrogen bonds. This view was obtained by rotating Fig. 2b counter clockwise 145° around Y-axis. j, Detailed interactions between Rco1_L PHD2 and Rpd3 with associated residues represented as sticks. Yellow dashed lines stand for polar interactions.