Bioinformatics and Evolution of Vertebrate XXXX and Opioid Receptors.

@entity1 @entity1931 @entity55393 @entity6253 @entity26010
UNASSIGNED: G protein-coupled receptors (GPCRs) are ancestrally related membrane proteins on cells that mediate the pharmacological effect of most drugs and neurotransmitters. GPCRs are the largest group of membrane receptor proteins encoded in the @entity1 genome. One of the most famous types of GPCRs is the opioid receptors. Opioid family receptors consist of four closely related proteins expressed in all vertebrate brains and spinal cords examined to date. The three classical types of opioid receptors shown unequivocally to mediate analgesia in animal models and in @entity1 are the mu- ( @entity6253 ), delta- (DOR), and kappa-(KOR) opioid receptor proteins. The fourth and most recent member of the opioid receptor family discovered is the @entity26010 or @entity55393 (ORL). The role of ORL and its ligands in producing analgesia is not as clear, with both analgesic and @entity1931 effects reported. All four opioid family receptor genes were cloned from expressed mRNA in a number of vertebrate species, and there are enough sequences presently available to carry out bioinformatic analysis. This chapter presents the results of a comparative analysis of vertebrate opioid receptors using pharmacological studies, bioinformatics, and the latest data from @entity1 whole-genome studies. Results confirm our initial hypotheses that the four opioid receptor genes most likely arose by whole-genome duplication, that there is an evolutionary vector of opioid receptor type divergence in sequence and function, and that the @entity6253 gene shows evidence of positive selection or adaptive evolution in @entity1 .
