Fig. 2.

Crystal structure of full-length mSAMHD1 iso1 in complex with GTP and dGTP (2-Allo). a Surface representation of mSAMHD1 tetramer in three orthogonal views. Each subunit is shown in a different color (purple, orange, red, and green) with SAM domains highlighted. b Surface representation of the 2-Allo structure showing the allosteric binding pocket at the interface of three subunits (purple, red, and green). GTP and dGTP are shown with red sticks and the SAM-to-HD inter- and intra-subunit interactions are highlighted with selected interface residues shown in sticks. c Transparent surface representation of the SAM domain (lime green) capping the allosteric site