OVERVIEW OF PROSTAGLANDIN SYNTHASE

Th structure seen here is prostaglandin synthase from ovine seminal vesicles.  For a quick review of the chime mouse commands that can be used to translate, rotate, and zoom in on the molecule you can go to the mouse control summary.  

Each monomer of this dimeric structure contains 576 amino acids.  The structure to the right shows that prostaglandin synthase contains almost 40% helical residues and virtually no organized beta-sheets (3).  

There are three distinct folding units found in this molecule.  The first folding unit (residues 33-72) is a compact domain held together by three intra-domain disulfide bonds.  Folding unit one is covalently linked to the main body of the protein by a disulfide bridge between CYS 37 & CYS 159 . This domain is quite similar to that of the epidermal growth factor (EGF) thought to be responsible for initiating or maintaining protein-protein interactions.  The intra-molecular disulfide bonds can be seen: CYS 36-CYS 47, CYS 41-CYS57, and CYS 59-CYS69 (3).

The second folding unit (residues 73-116) contains four right handed helices that are believed to form the motif for insertion into the lipid bilayer (4).

Residues 117-587 form the third, or catalytic, domain (3).    This is the largest of all of the folding units and contains the active sites for the cyclooxygenase and peroxidase activities.  The catalytic domain contains a heme at the apex of the cyclooxygenase active site (4).  The catalytic domain is composed of two lobes.  The larger lobe  is build around helices H5 and H6 which grip H2 in   'tweezer' fashion.  Packed around this core are H3, H10, H18, and H19.  The smaller lobe is a bundle formed by H1, H8, H12, H14, H15, and H16 (3).  The next page shows a closer look at the interaction between prostaglandin synthase and the ER lumen.

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