Encounter agonistic

In all cases, the molar concentration at which blockade of an agonist response is first encountered is a reasonable indication of the molecular potency of the antagonist, with the possible exception being allosteric modulators that block receptor signaling but increase the affinity of the receptor for the agonist. 

A difficulty encountered in such work, and one that has to be considered in any study of the relationship between the concentration of an agonist and its action, is the occurrence of desensitization. The response declines despite the continued presence of the agonist. Several factors can contribute. One that has been identified in work with ligand-gated ion channels is that receptors occupied by agonist and in the active state (AR ) may isomerize to an inactive, desensitized, state, ARd. This can be represented as ... 

Van Santen HM, Benoist C, Mathis D Number of Treg cells that differentiate does not increase upon encounter of agonist ligand on thymic epithelial cells. J Exp Med 2004 200 1221-1230. 

The precise effects of territorial scent marks on conspecifics are still a matter of debate. They may warn of a possible agonistic encounter and/or induce a state of increased probability to loose a fight. Gosling (1982) proposed that an intruder matches the scent of a competitor, or of a mark it is seen to have made, with that of other marks nearby. If the odors match, the competitor is probably... 

The only evidence to date for a male pheromone in spiders was presented by Ayyagari and Tietjen (1986), who obtained an extract from male S. ocreata silk that mediated agonistic encounters between males. The pheromone was not identified, but the authors concluded that two different components must be present, one apolar and the other of medium polarity. 

The kinetics of such FRET recordings of agonist-induced conformational changes in GPCRs are remarkably similar. In all instances where we have studied receptors for small ligands such as adrenaline or adenosine, the signals occurred with half-lives of 30-50 ms. The only exception encountered so far is the PTH receptor, which showed an activation half-life in... 

The (i-carbolinc skeleton with its 9H-pyrido[ 3,4-fr ]indole (29) is frequently encountered in pharmacology due to its activity in the central nervous system at serotonin receptors. It also shows prominent biological properties at the benzodiazepine receptor (BzR) [45]. ZK 93423 (30) remarkably amplifies the agonist activity of such compounds towards BzR. 1,2,3>9-Telrahydro-(>-carbolines are common precursors of (i-carbolines [46]. 1,3.4,9-Tetrahydro-... 

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