Refinement of the gonadotropin releasing hormone receptor I homology model by applying molecular dynamics

Sexual maturation of human cells in ovaries and prostate is linked to the biochemical cascade initiated by the activation of cell receptors through the binding of Gonadotropin Releasing Hormone (GnRH). The GnRH receptors (GnRHR) are part of the rhodopsin G-protein coupled receptor (GPCR) family and consist of seven trans-membrane helical domains connected via extra- and intra-cellular segments. The GnRH-GnRHR complex has been implicated in various forms of prostate and ovarian cancer. The lack of any structural data about the GnRH receptor impedes the design of antagonists for use in cancer treatment. The aim of the study is to devise a model of GnRHR to be used further for the design of improved peptide/non-peptide GnRH analogues and, to our knowledge provide new structural information regarding the extracellular loop 2 (ECL2) that acts a regulator of ligand entry to GnRHR. The common structural characteristics, of the members of the rhodopsin family of GPCRs, have been employed for the construction of a homology model for GnRHR. Structural information from the human β2-adrenergic receptor, as well as rhodopsins have been used in order to create a theoretical model for GnRHR. Furthermore, molecular dynamics (MD) simulations have been employed for the refinement of the model and to explore the impact of the bilayer membrane in GnRHR conformation.