downregulation

(redirected from Receptor down-regulation)
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Cell biology The reduction of a cell’s response to a hormone or other ligand by internalizing its cognate receptor and degrading it within a coated pit; downregulation is a mechanism by which receptors respond to an excess of ligands
Genetics The decrease of a gene’s transcriptional machinery usually by a DNA-binding protein that acts on a regulatory region

down·reg·u·la·tion

(down-reg-yū-lā'shŭn)
Development of a refractory or tolerant state consequent on repeated administration of a pharmacologically or physiologically active substance; often accompanied by an initial decrease in affinity of receptors for the agent and a subsequent diminution in the number of receptors.
References in periodicals archive ?
(2012) have also collected several hundred examples of nonmonotonic dose response curves (representing many classes of environmental chemicals) that have been observed in cultured cells, animals, and even human populations, Most important, they reviewed the voluminous endocrine literature on how and why nonlinear responses manifest at different levels of biological complexity, including the combination of competing monotonic responses (such as enhanced cell proliferation and cytotoxicity), the expression of cell-and tissue-specific cofactors and receptors, and receptor down-regulation, desensitization, and competition.
"It is not due to receptor down-regulation or up-regulation."
These polymorphisms strongly influence the degree of agonist-mediated receptor down-regulation. Whereas Q27E induces complete resistance to downregulation in combination with R16, R16G increases agonist-mediated receptor down-regulation in both haplotypes (5).
Very low doses can stimulate the production of more receptors (receptor up-regulation), resulting in an increase in responses, whereas higher doses (within the typical toxicologic range of chemical testing) can inhibit receptors (receptor down-regulation), resulting in a decrease in responses (Welshons et al.

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