Lect24.25.CellSignaling

Lect24.25.CellSignaling - LECT 24 and 25: CELL SIGNAL...

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LECT 24 and 25: CELL SIGNAL TRANSDUCTION Cells respond to molecular cues they receive: from neighboring cells or extracellular matrices (paracrine factors), from the circulation (hormones and metabolites), and from outside the body (sensory inputs). Some messengers, e.g. nuclear hormones, directly permeate the cell and interact with nuclear targets to effect responses. Most messengers bind to cell surface receptors, which transduce signals through intermediate proteins and messengers to ultimately effect changes in the cytoplasm and in the nucleus. The signal is often amplified during transduction, and feedback processes terminate or limit the response. Cell surface signaling receptors largely fall into several categories: …7-TM G-protein-coupled receptors (GPCRs) …Receptor protein kinases, including receptor tyrosine kinases (RTKs) …Others
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Second Messengers Are Synthesized or Mobilized During Signaling
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MANY SECOND MESSENGERS ACTIVATE SERINE/THREONINE PROTEIN KINASES Each S/T-protein kinase phosphorylates exposed serine or threonine residues within a consensus sequence. E.g. ------Arg-Arg-Xxx-Ser-Xxx------- ------Arg-Arg-Xxx-Ser-Xxx------- HO-P=O O- -O- ATP ADP PKA
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7-TM GPCRs Are Numerous and Mediate Many Biological Functions
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7-TM GPCRs Are Numerous and Mediate Many Biological Functions GPCRs couple to heterotrimeric G proteins to mediate signaling Activated β -adrenergic receptor activates Gas, which in turn activates adenylate cyclase (AC), which synthesizes 2o messenger cAMP, which activates protein kinase A
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The Heterotrimeric G Protein Activation/Inactivation Cycle
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Phospholipid Hydrolysis by PhospholipaseC Generates Two Second Messengers There are several classes of PLC. One class is regulated by GPCRs
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PLC-Derived Second Messengers Activate Protein Kinase C
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ODORANT RECEPTOR STIMULATION OPENS cAMP-GATED CATION CHANNEL
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This note was uploaded on 02/14/2012 for the course BIO 710L taught by Professor Goldfarb during the Fall '10 term at Iowa State.

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Lect24.25.CellSignaling - LECT 24 and 25: CELL SIGNAL...

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