Cloned human receptors

Millan Ml, Maiofiss L, Cussac D, Audinot V, Boutin JA, Newman-Tancredi A. (2002) Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. I. A multivariate analysis of the binding profiles of 14 drags at 21 native and cloned human receptor subtypes. J Pharmacol Exp Ther 303 791-804. 

The existing DA receptors have been fully characterized as 7-trans-membranal G protein-coupled receptors in their five subtypes and multiple variants (Table 14-1]. The availability of cloned human receptors will permit the discovery of more selective drugs for the purposes already partially achieved in depression by the relatively nonselective agonists and antagonists described earlier. New Dj postsynaptic agonists and autoreceptor-selective Dj antagonists may offer the best prospects. It is entirely likely that further subtypes and variants will be added to the present list (P. Seeman and Van Tol 1994 Sibley and Monsma 1992]. 

At the molecular level, the compound would be screened for activity on the target, for example, receptor binding affinity to cell membranes containing the homologous animal receptors (or if possible, on the cloned human receptors). Early studies would be done to predict effects that might later cause undesired drug metabolism or toxicologic complications. 

Antagonism effectiveness was obtained by monitoring the ability of selected experimental agents to inhibit stimulation of [35S]GTP-y-S binding in guinea pig caudate and in cloned human receptors. Testing results are provided in Tables 2 and 3. 

CLONED HUMAN RECEPTORS AS DRUG DISCOVERY TARGETS... 

In the future, models will exist which will link constants for in vitro binding to cloned human receptors (Kd), data from in vitro functional assays (IC50) and animal and human in vivo EC50 values. A composite prediction matrix will be applied rapidly and accurately to the process of synthesis of new compounds for phase I testing. 

The cloned human receptor was stably expressed in murine fibroblast cells (L-MCTK )cells whereas the Ala-242 mutant receptor was expressed in COS-7 cells. 

A series of 11 ergolines was tested for affinity for native and cloned rat- and cloned human receptors. Nine of the ergolines were tested for affinity for the mutant receptors. The series consisted of compounds with an unsubstituted indole nitrogen (Ni-H) and of their alkyl substituted congeners (Nj-Me, N,-iPr). H-DOI and H-ketanserin were used to label the binding sites. 

Several human receptors for the neurohypophyseal hormones have been cloned and the sequences elucidated. The human V2 receptor for antidiuretic hormone presumably contains 371 amino acids and seven transmembrane segments and activates cycHc AMP (76). The oxytocin receptor is a classic G-protein-coupled type of receptor with a proposed membrane topography also involving seven transmembrane components (84). A schematic representation of the oxytocin receptor stmcture within the membrane is shown in Eigure 4 (85). 

In general the receptor nomenclature used is consistent with the recommendations of the various International Union of Pharmacology (lUPHAR) Committee on receptor nomenclature (19,20). In some cases the human receptor has been cloned. By convention, pharmacologicaUy defined receptors are shown ia capital letters cloaed receptors ia lower case letters. 

Chen, W.-J., Armour, S., Way, J., Chen, G., Watson, C., Irving, P., Cobb, J., Kadwell, S., Beaumont, K., Rimele, T., and Kenakin, T. P. (1997). Expression cloning and receptor pharmacology of human calcitonin receptors from MCF-7 cells and their relationship to amylin receptors. Mol. Pharmacol. 52 1164-1175. 

The cloned human GAL2 receptor binds porcine [125I]-[Tyr26]galanin and couples readily to Gq/Gn-type G proteins or related pathways in vitro. Under certain conditions, GAL2 also appears to couple with G/G0-and G12-type proteins [1, 2]. Specific examples of... 

Y2 receptors were originally cloned from human SMS-KAN cells. Later cloning studies in rats demonstrated that the cloned Y2 receptor is also the molecular correlate of a previously proposed PYY-preferring receptor in the gastrointestinal tract. Messenger RNA for the Y2 receptor has been detected in various parts of the CNS, whereas only low levels of Y2 mRNA were found in human peripheral tissues. 

Felder CC, Briley EM, Axelrod J, Simpson JT, Mackie K, Devane WA. Anandamide, an endogenous cannabimimetic eicosanoid, binds to the cloned human cannabinoid receptor and stimulates receptor-mediated signal transduction. Proc Natl Acad Sci USA 1993 90 7656-7660. 

Raynor K, Kong H, Mestek A et al. Characterization of the cloned human p. receptor. J Pharmacol Exp Ther 1995 272 423-428. 

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