Fig. 2: The crystal structure of PbSRD5A and coordination of NADPH.
From: Crystal structure of steroid reductase SRD5A reveals conserved steroid reduction mechanism
a The overall structure of PbSRD5A. Two perpendicular views are shown. The seven transmembrane segments are divided into TM1 (lightblue), TM2-4 (green), and TM5-7 (yellow). The extracellular and intracellular short alpha helices (ECH and ICH) are colored wheat. The short antiparallel beta strands are colored blue. The loop regions are colored white. b 2Fo-Fc map for monoolein (orange mesh) and NADPH (cyan mesh) are both contoured at 1.0σ. The two black lines show the approximate location of the lipid bilayer. The cavity is circled in an electrostatic surface representation. c NADPH fits into the density map shown in b. Nicotinamide and adenine groups are labeled. d Coordination of NADPH by polar residues of PbSRD5A. The residues that are hydrogen-bonded to NADPH are shown in yellow sticks. e Functional validation of residues coordinating NADPH in PbSRD5A. Enzyme activities were measured by the percentage of 5α-DHP reduced from [3H]-labeled progesterone in vitro within 1 h detected by HPLC. Data are mean±s.d. derived from technically independent experiments in duplicate. Each experiment was reproduced three times on separate occasions with similar results.
