Fig. 5: An IP6-binding site in human INTS4-INTS9-INTS11 complex (ICM).
From: Inositol hexakisphosphate is required for Integrator function
a Alignment of selected sequences for IntS9 and IntS11 residues in the IP6 binding site. Residues that have ionic interactions with the phosphate groups on IP6 are indicated with the red dots. Dm D. melanogaster, Aa Aedes aegypti, Hs H. sapiens, Xt Xenopus tropicalis, Dr Danio rerio. b Cryo-EM density for IP6 in human ICM (EMDB 12159)19. An IP6 molecule was built into the density and subjected to real-space refinement. c Overlay of the structures of Drosophila ICM (in color) and human ICM (gray, PDB entry code 7BFP) near the IP6 binding site. The human ICM structure likely has a registering shift of two residues for residues 504–509 of INTS9. Arg504, Lys508, and Arg509 of Drosophila IntS9 would be equivalent to Ala506, Lys510, and Arg511 instead of Val504, Pro508, and Phe509 of human INTS9, which would also be consistent with the sequence conservation in this region (a).
