Term
| Describe and provide an example of drug selectivity |
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Definition
| Selectivity was first demonstrated by the use of medicinal plants. Later selectivity was defined as the interaction of different chemicals with cellular receptors. |
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Term
| Describe the 4 postulates of receptor theory. |
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Definition
1) it must possess structural and steric specificity
2) it is saturable and finite
3) it possesses a high affinity for an endogenous ligand at physiological concentrations
4) binding of an endogenous ligand results in some physiological consequence
**NOTE** Not all drug binding to cellular macromolecules represents a "drug-receptor" interaction |
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Term
| Identify and differentiate between the five classes of receptors. |
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Definition
1) Cytosolic receptors
2) Transmembrane enzyme-containing receptor
3) Transmembrane enzyme-linked receptor
4) Transmembrane ion channel receptor
5) G-protein coupled receptor |
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Term
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Definition
| Requires entry of the ligand into cytosolic space where receptor resides. Ligand-receptor binding often results in translocation into the nucleus, resulting in binding to DNA and regulation of transcription. Eg. glucocorticoids |
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Term
| Transmembrane enzyme-containing receptor |
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Definition
| Ligand binds to the portion of the receptor exposed to the outer membrane of the cell resulting in activation of an enzymatic component of the receptor |
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Term
| Transmembrane enzyme-linked receptor |
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Definition
| Sometimes combined with transmembrane enzyme-containing receptor. The difference is that the receptor is a complex associated with a separate protein that possess enzymatic activity. |
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Term
| Transmembrane ion channel receptor |
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Definition
| Multi-subunit proteins that penetrate the membrane. Ligand binding results in biophysical alteration that attenuate or enhance the passage of ions across the membrane. |
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Term
| G-protein coupled receptor |
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Definition
| An extremely important group of receptors that modulate the effects of many important drugs. Ligand binds to the outer membrane domain of receptor, which initiates a cascade of events modulated by G-protein. |
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Term
| Provide an explanation for the organ-specific actions of drugs. |
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Definition
| Organ specific actions of drugs can often be related to the anatomical distribution of receptors. If a certain receptor is found on one organ, but not another a drug matching that receptor will only bind in the organ with the corresponding receptor. |
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