Assays function

AGONISTS THE MEASUREMENT OF AFFINITY AND EFFICACY IN FUNCTIONAL ASSAYS... 

The majority of functional assays involve primary signaling. In the case of GPCRs, this involves activation of G-proteins. However, receptors have other behaviors— some of which can be monitored to detect ligand activity. For example, upon stimulation many receptors are desensitized through phosphorylation and subsequently taken into the cell and either recycled back to the cell surface or digested. This process can be monitored by observing ligand-mediated receptor internalization. For... 

A useful method of weighting is through the use of an iterative reweighted least squares algorithm. The first step in this process is to fit the data to an unweighted model. Table 11.7 shows a set of responses to a range of concentrations of an agonist in a functional assay. The data is fit to a three-parameter model of the form... 

The ICS0 is used in a version of the Cheng-Prusoff equation for functional assays. Thus, the apparent Kb (apparent equilibrium dissociation constant for the antagonist-receptor complex) is given by... 

Ag, convention for the equilibrium dissociation constant of an antagonist-receptor complex usually determined in a functional assay denoting antagonism of a physiological response, although it can be associated with an antagonist when it is used in other types of experiment. It has units of M and is the concentration that occupies half the receptor population at equilibrium. It also can be thought of as the reciprocal of affinity. 

Free drug concentration description of, 36-37 measurement of, in receptor compartment, 39 Frovatriptan, 163f Full agonism, 200-202 Full agonists affinity of, 261 description of, 27—30 dose-response curves for, 90, 200-202 Furchgott method for affinity measurements, 261 potency ratios for, 202—204, 219—220 Functional assays... 

Functional assays (continued) dissimulation, 87-88 group I, 81-82 group II, 81, 83 group III, 83-84 group IV, 84 isolated tissues for, 81 membrane, 81 output from, 79... 

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