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. Author manuscript; available in PMC: 2009 Nov 1.
Published in final edited form as: Mol Genet Metab. 2008 Sep 23;95(3):152–162. doi: 10.1016/j.ymgme.2008.08.004

Fig. 5. Three-dimensional model of human ASM.

Fig. 5

All images were built using the Swiss-PDB Viewer and POV-Ray programs. (A) Domain structure of human ASM. The saposin B-like domain is in gold, and the metallophosphoesterase-like domain is in blue. (B) Locations of functional regions within the metallophosphoesterase-like domain. The putative active site motif is in red, the putative sphingomyelin-binding motif is in green, and one of the three putative zinc-binding motifs (HXXGHXXXGH) is in pink. Note that these three motifs are adjacent to one another, and form an “active site pocket” in the center of the domain. (C) Depiction of the H421Y and R496L mutations. The putative active site pocket backbone is in red. Two of the three histidines involved in the critical zinc-binding site are shown in pink (H425 and H430), and the two NPD mutations are depicted in purple. Note that the H421Y mutation alters the first histidine in this important zinc-binding site, and the R496L mutation is close to the active site. (D) Depiction of the ΔR608 mutation, which lies within 3 Å of two cysteine residues involved in intramolecular disulfide bonds.