The 5-HT1E receptor. Receptor structure and ligand interactions.

Abstract

5-HT (5-Hydroxytryptamine; Serotonin) is the neurotransmitter with the highest number of known receptors in humans, and the importance of 5-HT is also reflected in the number of species using 5-HT as a signalling molecule and the number of 5-HT receptors found within each species. 15 human 5-HT receptors have at this date been characterised and classified into seven 5-HT receptor families. Six of the 5-HT receptor families encode G-protein coupled receptors (GPCRs), while one family, the 5-HT3 family, contains ionotropic receptors. The 5-HT receptors may play potential roles in conditions such as depression and anxiety, in neuroendocrine function and thermoregulation, vasoreactive headaches, sexual behaviour, food intake, and immune function. The human 5-HT1E receptor gene was cloned in 1992. The gene encodes a G-protein coupled receptor of 365 amino acids that belongs to the rhodopsin family of GPCRs. The detailed three-dimensional structure of the 5-HT1E receptor is not known, and little is known about the function and distribution of the 5-HT1E receptor protein. No selective ligands for the receptor have been described. Insight into ligand-receptor interactions is of pivotal importance for designing new ligands with therapeutic potential and in order to study these interactions, three-dimensional structural information about the receptor structure is necessary. The x-ray crystallographic structure of bovine rhodopsin shares the same three-dimensional topology as the 5-HT1E receptor, providing the opportunity of using the homology modeling approach to construct a three-dimensional model of the 5-HT1E receptor. In the present study, a model of the 5-HT1E receptor was constructed using molecular modeling techniques and docking of a series of ligands into the putative binding site of the 5-HT1E receptor was performed.