| be involved in a variety of pathological disorders such as pain, fever and
inflammation. These receptors are important drug targets, but design of subtype
specific agonists and antagonists has been partially hampered by the absence
of three-dimensional structures for these receptors. To understand the
molecular interactions of the PGE2, an endogen ligand, with the EP1 receptor,
a homology model of the human EP1 receptor (hEP1R) with all connecting
loops was constructed from the 2.6 Å resolution crystal structure (PDB code:
1L9H) of bovine rhodopsin. The initial model generated by MODELLER was
subjected to molecular dynamics simulation to assess quality of the model.
Also, a step by step ligand-supported model refinement was performed,
including initial docking of PGE2 and iloprost in the putative binding site,
followed by several rounds of energy minimizations and molecular dynamics
simulations. Docking studies were performed for PGE2 and some other related
compounds in the active site of the final hEP1 receptor model. The docking
enabled us to identify key molecular interactions supported by the mutagenesis
data. Also, the correlation of r2=0.81 was observed between the Ki values and
the docking scores of 15 prostanoid compounds. The results obtained in this
study may provide new insights toward understanding the active site conformation of the hEP1 receptor and can be used for the structure-based
design of novel specific ligands. |