Prostaglandin E2 synthase
Microsomal glutahione transferase 1 (MGST1) is a detoxification enzyme responsible for conjugation of glutathione to electrophilic substances. It can be considered as the prototype member of a recently discovered superfamily of proteins called MAPEG, Membrane Associated Proteins in Eicosanoid and Gluathione metabolism. As demonstrated in our previous work MGST1 can form large and well-ordered 2-D crystals under specific conditions. 3-D maps of the protein at 6 Å from two different crystals forms clearly showed for the first time the architecture of a MAPEG protein. MGST1 is homotrimer with 12 transmembrane alpha-helices. Each monomer contributes with helices arranged as left-handed four helix bundles. Six of the helices in the trimer form an inner triangular core structure with the remaining six helices at more peripheral locations. The fold is completely different from that of soluble glutathione tranfersases in spite of the fact that they catalyze similar reactions and to some extent also share substrate specificity. On the other hand, the fold of the MGST1 trimer resembles that of cytochrome c-oxidase subunit 1, a protein with neither functional nor sequence similarity.
©2003 Webmaster. All rights reserved.