Non-polar, diffuse across the membrane. Its an intracellular receptor
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3 domains
Transcriptional regulation; DNA bonding; ligand binding
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Ligand binding
Conformational change, inhibitory complex dissociates, receptor binds to DNA, associated with coregulator protein complex.
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Coregulator protein complex
Activators and repressors of transcription
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Selective receptor modulators
Drugs that act as agonists in some tissues while acting as antagonists in other tissues
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Raloxifene
Selective estrogen receptor modulator. Prevents loss of bone density while acting as an estrogen receptor antagonist in breast and unterine tissue.
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Steroid hormones
E.g. cortisol, testosterone and vitamin D.
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Thyroid hormones
E.g. T4 or T3. Regulate body temperature, metabolism and heart rate.
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Retinoids
Synthesised from vitamin A. Used to treat and prevent deficiency. Small hydrophobic molecules,
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Steroid receptors
Bound to Hsps, translocation to the nucleus, bind as homodimers, act as upstream promoter sites.
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Agonists
Hydrophobic, diffuse freely
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Agonists
Bind to ligand-binding domains, act as molecular switch.
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PPARs
Function as transcription factors regulating the expression of genes. There are 3 types: a,b,y.
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Fibrates PPARs agonists
E.g. Lopid. Used for type 2 diabetes, and atherosclerosis, to decrease serum triglycerides.
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Glucocorticoid Receptors
E.g. cortisol. Involved in inflammatory disorders of the gut and autoimmune disorders. Due to upregulation of anti-inflammatory proteins.
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Dexamethasone
Anti-inflammatory and immunosuppressant effects used to treat allergic reactions
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Mifepristone
Antagonizes the effects of cortisol.
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Cyproterone acetate
Anti-androgen. Used to treat severe hypersexuality and sexual deviation in men. Inhibits spermatogenesis.
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Thyroid receptors
Encoded by two genes a & b. React with retinoid X receptors. Mutant receptors lead to hypothyroidism e.g. goiter
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Levothyroxine
Thyroid receptor agonist, used to treat hypothyroidism, stop thryoid hormone production.
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Oestrogen receptors
Key regulators in cell growth and differentitation. Mediated by ERa and ERb. Breast cancers are dependent on the release of oestrogen.
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Tamoxifen
Oestrogen receptor antagonist in breast tissue (co-repressor)and acts as agonist in other tissues (co-activator). Must be metabolised by cytochromes
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Vitamin D receptors
Regulate the absorption of calcium, iron, zinc, magnesium and phosphate. Important in bone mineralization. Used to treat Rickets. Suggests that high levels of vitamin D in the blood links with reduced risk of colorectal cancer
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Migepristone
Brings about an abortion during pregnancy up to 49 days. In the presence of progesterone, it acts as a competitive progesterone receptor antagonist.
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Other cards in this set
Card 2
Front
Variable amino-terminal; highly conserved DNA-binding; less conserved carboxyl-terminal ligand binding
Back
Domains in nuclear receptors
Card 3
Front
Progesterone, estrogen, glucocorticoid, androgen and mineralocorticoid
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