Domain structure of DGCR8 and sequence alignment of the heme-binding domains.

(A) Domain structure of human DGCR8 and schematics of the NC1 and HBD constructs used in this study. (B) Schematic of how the DGCR8 HBD binds Fe(III) heme. (C) Sequence alignment of bat star, frog and human HBDs. Identical residues are shaded in black. Residues that are identical only between two species are shaded in gray. Red stars denote residues in human HBD known to be important for heme binding. Secondary structure assignments derived from the crystal structure of frog dimerization domain are shown below the sequences, with β-strands as green arrows and loops as bars.