5-HT2 receptors.

5-HT(2) receptors are G-protein coupled receptors that currently comprise three subtypes: 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptors. The subtypes are related in their molecular structure, amino acid sequence and signaling properties. 5-HT(2A) and 5-HT(2C) receptors have a widespread distribution and function in the central nervous system. 5-HT(2A)and 5-HT(2C) receptor antagonism is a property of certain antipsychotic and antidepressant drugs. 5-HT(2B) receptors have a restricted expression in the central nervous system. They have an important role in embryogenesis and in the periphery. In this article, selected aspects of 5-HT(2) receptor research are reviewed for each subtype under three main headings : (i) genes, protein structure and receptor signaling; (ii) receptor localization with emphasis on the CNS and (iii) compounds. The general discussion reflects on the reasons for the limited success in the clinic of 5-HT(2) receptor subtype selective drugs.