Mechanisms of hormone action

Mechanisms of - • Water-soluble hormones(polypeptide protein and most amino acid hormones bind to a receptor protein on the plasma membrane of

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Mechanisms of hormone action Hormones circulating in the blood diffuse into the interstitial fluids surrounding the cell. Cells with  specific receptors for a hormone respond with an action that is appropriate for the cell. Because of  the specificity of hormone and target cell, the effects produced by a single hormone may vary among  different kinds of target cells. Hormones activate target cells by one of two methods, depending on the chemical nature of the  hormone:  Lipid-soluble hormones (steroid hormones and hormones of the thyroid gland) diffuse  through the cell membranes of target cells. The lipid-soluble hormone then binds to a  receptor protein that in turn activates a DNA segment that turns on specific genes. The  proteins produced as a result of the transcription of the genes and subsequent translation of  mRNA act as enzymes that regulate specific physiological cell activity.
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Unformatted text preview: • Water-soluble hormones (polypeptide, protein, and most amino acid hormones) bind to a receptor protein on the plasma membrane of the cell. The receptor protein in turn stimulates the production of one of the following second messengers: • Cyclic AMP (cAMP) is produced when the receptor protein activates another membrane-bound protein called a G protein. The G protein activates adenylate cyclase, the enzyme that catalyzes the production of cAMP from ATP. Cyclic AMP then triggers an enzyme that generates specific cellular changes. • Inositol triphosphate (IP 3 ) is produced from membrane phospholipids. IP 3 in turn triggers the release of Ca 2+ from the endoplasmic reticulum, which then activates enzymes that generate cellular changes....
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This note was uploaded on 11/10/2011 for the course PT 101 taught by Professor Staff during the Spring '10 term at Texas State.

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