Week 9 Handout

Week 9 Handout - BIBC 100 Week 9 Jonathan Goldstone...

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BIBC 100 Week 9 Jonathan Goldstone [email protected] Signal Transduction Cells must convert extracellular signals into intracellular signals that alter cell behaviour o ie antigens, light, hormones, nutrients, growth factors, neurotransmitters Requirements for signal transduction o Specificity o Amplification o Desensitization/Adaptation o Integration Fig 12-2 – summary slide of signal transduction (you only need to know two types) o G protein- coupled  receptors o Receptor  tyrosine  kinase o Receptor guanylyl cyclase o Adhesion receptor (integrin) Fig 13-1 B and T – example of receptor tyrosine kinase o Extracellular ligand-binding domain and intracellular tyrosine kinase domain o Phosphorylates Tyr residues both in receptor  itself and in target proteins o Structure 2 identical extracellular α-subunits – insulin binding sites 2 β-chains – Tyr kinase activity o Mechanism of action for Insulin receptor Insulin binds and leads to conformational change in receptor Conformational change leads to autoP (crossP) of self Targets 3 Tyr residues on intracellular domain of receptor o Each β-chain phosphorylates the other one Conformational change reveals substrate binding sites o Increases kinase activity of enzyme Phosphorylation of IRS-1 – Insulin Receptor Substrate 1 o Goes on and activates many downstream effects P-Tyr on IRS-1 binds to and activates PI-3 kinase o PI = phosphatidyl inositol o PI-3 kinase converts PIP2 into PIP3 PIP3 binds and activates Protein Kinase B PKB leads to the mobilization of glucose transporters Glycogen synthesis Glycogen synthase kinase (GSK) is inactive when
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BIBC 100 Week 9 Jonathan Goldstone [email protected] phosphorylated PKB phosphorylates GSK3, therefore inactivating it When glycogen synthase (GS) is phosphorylated, it is inactive When GSK3 is phosphorylated, it cannot phosphorylate GS into its inactive form, therefore GS stays active and makes glycogen!
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This note was uploaded on 01/07/2010 for the course BIBC BIBC 100 taught by Professor Buehler during the Spring '09 term at UCSD.

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Week 9 Handout - BIBC 100 Week 9 Jonathan Goldstone...

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