ADENOSINE RECEPTOR SUBTYPES - CHARACTERIZATION AND THERAPEUTIC REGULATION

Adenosine receptors (ARs) are members of the G protein-coupled recepto r family and mediate the multiple physiological effects of adenosine. Currently, four AR subtypes have been cloned: A(1)AR, A(2a)AR, A(2b)AR , and A(3)AR. All subtypes are distinctly distributed throughout the b ody and AR agonists and antagonists have potential therapeutic utility . Knowledge of AR amino acid structure has been utilized in mutagenesi s studies to identify specific receptor regions that interact with dis tinct classes of ligands. Cloning of ARs has also permitted receptor r egulatory processes such as desensitization to be studied in greater d etail, in particular, the molecular mechanisms underlying this event. Cloning of the human A(1)AR has revealed that alternate splicing gener ates distinct receptor transcripts. The existence of a particular tran script in a tissue or cell apparently regulates the level of A(1)AR ex pression in the tissue. This review focuses on these aspects of AR str ucture and function and their therapeutic regulation.