Physiology 3140A Chapter Notes -Base Pair, Inositol, Chromophore
4 Feb 2014
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Document Summary
Ligands: small hydrophobic molecules that have very different structures and physiological functions, all act through similar mechanism. Interaction of hormone with receptor converts the transcriptionally inactive receptor protein into a form that recognizes and binds to specific dna sequences: regulatory regions of target genes. Interactions lead to alterations in: the rate of gene transcription. Both increased and decreased: magnitude of which depends on the cellular promoter, context of the bound receptor, steroid receptors bind as protein dimers (receptor pairs) to specific gene hormone responsive. Examples of steroid antagonists: tamoxifen, anti-estrogen drug for treatment of breast cancer, currently largest selling anti-cancer drug, ru486, abortion drug, anti-progesterone also used in cancer treatment. Ligand binding domain overlaps with other functional domains required for: dimerization, transcriptional actiation, interaction with the heat shock proteins, sequences required for nuclear localization. Activation of hormone receptors: biologically inactive, ligand-free receptors are localized predominantly in the cell nucleus, not tightly bound to dna.
