Ligands agonists

To denote the mechanism whereby the position of the equilibrium between two distinct forms of the receptor changes in the presence of a ligand (agonist or antagonist) for which the affinity of the forms is different. 

Schematic diagram of the modification of protection from modification by application of a reversible ligand (agonist or antagonist, ). The reversible binding site specific ligand slows the rate at which the MTS reagent modifies the thiolate group of the introduced cysteine...

Centrally Acting Dopamine D2 Receptor Ligands Agonists... 

Dooley, C. and Houghten, R. (Torrey Pines Institute for Molecular Studies) Novel mu opioid receptor ligands agonists and antagonists, W09640208 (1996) US5641861 (1997) US5919897 (1999). 

Cholecytokinin ligands - agonists of the central CCK receptors cause anxiety and precipitate panic attacks in predisposed individuals. Two types of CCK receptors have been identified, CCK-A and -B (from the alimentary tract and brain respectively), both of which occur in the mammalian brain. CCK-B agonists initiate anxiety while the antagonists are anxiolytic in both experimental and clinical situations. So far the poor bioavailability and side effects have limited their clinical development. 

In addition to ligand (agonist)-based activation, an important component of sensory perception is the cessation or reduction of signaling that is directly... 

Fig. 6. A multistate model of receptor function with three states. The receptor population consists of an inactive receptor conformation (R) in equilibrium with two (or more) active receptor conformations (R and R ). Each active conformation can differentially activate effector mechanisms, leading to response 1 or response2 in the absence of an agonist. Two isomerization constants (L and M) define the propensity of the receptor to adopt an active conformation in the absence of a ligand. Agonists can differentially stabilize R vs R depending on the value of the equilibrium dissociation constants KA and KA relative to KA. Inverse agonists can also have differential effects on response 1 vs. response2 depending upon the relative values of L and M and of the affinity constants. Additional active states with additional isomerization and affinity constants can be added. Adapted from Leff et al. (86) and Berg et al. (22).

O-R ligand (agonist) [3] (A AD-R) [analeptic, analgesic (mouse abdominal relaxant), antiviral]... 

Wikstrom, H. (1992) Centrally acting dopamine D2 receptor ligands agonists. Prog. Med. Chem. 29, 185-216. 

In the field of 5HT-1A receptor ligands agonists and partial agonists abound, but pure antagonists remain scarce. The first such compound to become available was WAY-100135 (111)(457), which incorporates a lipophilic... 

Figure 9.15. Schematic outline of the basics of allosteric drug design in ligand agonists and antagonists.

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