ABSTRACT
The G-protein coupled peptide receptors as well as their ligands, endogenous peptides, are involved in regulation of many important physiological processes in the organism and therefore represent attractive targets for pharmaceutical investigation and drug design. With the completion of the human draft genome sequencing, it has become possible to take a comprehensive picture of all genes encoding both peptide receptors and peptides themselves. In the present study a first attempt has been made to carry out a comprehensive analysis of G-protein coupled peptide receptors and their respective endogenous peptide ligands in the human genome. We searched the genome sequence by means of sequential application of standard bioinformatical methods (such as homology search, hierarchical cluster analysis, building of hmm-profiles etc.) with the goal of identifying all the components of peptide ligand/receptor system in the human genome. As a result of this search it was concluded that the probable number of functional peptide receptors in the human genome is 218, and the probable peptide precursors' number is 126 amino acid sequences. These two groups include, respectively, 12 novel G-protein coupled peptide receptors and 10 novel peptide precursors, discovered in the present study. The probable biological functions of newly discovered candidates were determined based on the sequence similarity to the earlier known proteins. Classification of all peptide GPCRs and their ligands based on the ligand specificity was performed for all probable G-protein coupled peptide receptors. The issue of ligand-receptor specificity in the human genome is also discussed.
