D103 _lect20_C HL

D103 _lect20_C HL - Lecture 20 Signaling V Todays Topics...

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Page 1 Lecture 20 – Signaling V Today’s Topics Receptor tyrosine Kinases Hormone nuclear receptors Integration of Signals Reading: MBOC5e, p889-891; 921-945
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Page 2 Signaling by steroid, thyroid, retinoid, vitamin D receptors Hormones are chemical messengers that coordinate cellular activity. Two major families - steroid hormones, thyroid hormones / retinoids. Activate at very low concentrations - typically less than 1 ppb (1 ppb ~= 3 nM). •T h e small, hydrophobic nature permits them to diffuse through the cell membrane. Steroid hormones can persist in blood for hours, in fat for days . Over a hundred hormones function in a wide range of biological processes - e.g. reproduction - e.g. estrogen, testosterone. metabolic rate - thyroid hormone, growth hormone. stress - glucocorticoids, ACTH, CRF. blood pressure - aldosterone, renin, angiotensin, vasopressin. calcium homeostasis - vitamin D3, calcitonin, PTH. Some vitamins or vitamin derivatives are hormones, e.g. Vitamin A, Vitamin D3. Receptors are ligand-modulated transcription factors – receptors that function in the nucleus .
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Page 3 Nuclear hormone receptors super-family - general structure
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Page 4 Steroid hormone receptors - binding of ligand stimulates movement of receptor-ligand complex into nucleus to bind to DNA O H OH estradiol + ligand
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Page 5 Retinoid / thyroid / vitamin D hormone receptors - binding of ligand to receptor in nucleus converts receptor from repressor to activator (represses transcription) (activates transcription) Note - unlike androgen and estrogen receptors, the nuclear localization signal of the retinoid / thyroid / vitamin D hormone receptors is always unmasked and thus the
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This note was uploaded on 02/21/2009 for the course BIOL 05400 taught by Professor Taagepera,s during the Spring '09 term at UC Irvine.

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D103 _lect20_C HL - Lecture 20 Signaling V Todays Topics...

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