The aim is to improve the methods for development of drugs for GPCRs. The genes for known peptide binding GPCRs will be mutated with new technology and, along with a number of structurally similar orphan receptors, expressed in order to determine the structural requirements for ligand-receptor activation and identify new ligands. The first part involves characterization of the molecular basis for ligand-receptor activation for three distinct GPCR families with know liands. We will use a recently developed approach that involves insertion of high affinity metal ion binding sites in form of His Zn(II) sites in these receptors in sites located between TM segments of the receptor can systematically reveal helix-helix interactions. This enables us in a fast effective way determine the orientation and the interconnection of the 7 helix regions in the receptors. We believe that our studies will eventually lead to new classification of peptide binding GPCRs. The second approach is based on expressing a number of orphan GPCRs in our unique receptor expression systems in order to find a ligand. We will use the newly developed cytosensor microphysiometer measurement technology that is excellent for screening for new receptor ligands. We are also developing a technology that has not been earlier been used for GPCRs. This is a Biacore based surface plasmon resonance based biosenor technology. This approach enables direct detection and monitoring of bio-molecular binding events in real time without labeling and often without purifying the substances involved. If we have success with this technology, it could revolutionize the ligand identification process for GPCRs. The University of Latvia (LU) has molecular biology but there is no tradition, know-how or current on-going work on pharmacology or gene expression technologies. The key know-how in our proposal is based on modern receptor pharmacology, expression techniques and molecular modeling of receptor proteins. It is of great importance to bring this know-how to Riga. There is a modern fully equipped receptor pharmacology/gene expression laboratory at LU, but these facilities have not been used for research. This is thus a great opportunity to introduce a young scientist, with stable connection within the LU, to these technologies that are successfully applied in Uppsala. This would create a self-sufficient situation for LU providing possibilities for sustainable long research within the field. The technology would make a link the well working molecular biology unit at the LU and the effective chemical synthesis at IOS in Riga, potentially creating effective synergy.