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MCB Review Exam II Ji Woong Park
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Logistics This review covers lectures by Dr. Mercer, Nichols, and first and third lecture by Dr. Bose. It accounts for 60/100 points in the second exam. Be sure to not just study but be able to answer 2013 Exam II (at least for my section) – you will thank me on Tuesday. In addition, understand everything on this review slide as well. There will be NO math problem on this exam.
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Primary Active Transport: Na,K-ATPase 3 Na outward / 2 K inward / 1 ATP K m values: Na in ≈ 20 mM K out ≈ 2 mM Inhibited by digitalis and ouabain Palytoxin “ opens ” ion channel 2 subunits, beta and alpha (the pump) Two major conformations E1 & E2 Turnover = 300 Na + / sec / pump site @ 37 °C
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Unidirectional Transport Assays Cells growing in multi-well plates 1.Cells washed in isotonic buffered solution 2.Required transport inhibitor(s) added 3.Flux medium containing radioactive isotope added 4.At required times flux medium rapidly removed and cells washed (3-4 x) in ice-cold isotonic saline 5.Final wash removed, cells lysed and radioactivity and protein content of samples determined
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LIMITING JUNCTION/TIGHT JUNCTION
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CLAUDINS
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“GATING” OF CONNEXONS
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Aquaporins- ADH Stimulated Water Permeability
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SORTING SIGNALS
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10 Selectivity filter diversity
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11 Ion gradients and membrane potential Na117 K 3 Cl120 Anions 0 Total 240 Na 30 K 90 Cl 4 Anions 116 Total 240 [+ charge] = [- charge] 0 mV [+ charge] = [- charge] -89 mV How does this membrane potential come about?
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12 At Electrochemical Equilibrium: The concentration gradient for the ion is exactly balanced by the electrical gradient There is no net flux of the ion There is no requirement for any energy- driven pump to maintain the concentration gradient
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13 The Goldman Hodgkin Katz Equation Resting Vm depends on the concentration gradients and on the relative permeabilities to Na, K and Cl. The Nernst Potential for an ion does not depend on membrane permeability to that ion. The GHK equation describes a steady-state condition, not electrochemical equilibrium. There is net flux of individual ions, but no net charge movement. The cell must supply energy to maintain its ionic gradients.
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14 Currents During an Action Potential Time Course of Currents
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15 Sodium Channel Gating States
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Trypsin – a protease that cleaves after basic residues (R or K). Identifying a Protein by Mass Spectrometry on Its Tryptic Peptides Slide courtesy of Andrew Link Protein of Interest:
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Products from Trypsin digest. Identifying a Protein by Mass Spectrometry on Its Tryptic Peptides Slide courtesy of Andrew Link Average length of tryptic peptides = 10 aa residues
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Select an Individual Peptide in the Mass Spectrometer Identifying a Protein by Mass Spectrometry on Its Tryptic Peptides Slide courtesy of Andrew Link Performed by adjusting the electrical fields in the mass spectrometer.
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Impart energy to the peptide by colliding it with an inert gas (Argon or Helium). Identifying a Protein by Mass Spectrometry on Its Tryptic Peptides Slide courtesy of Andrew Link
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Measure the masses of the fragment ions. Identifying a Protein by Mass Spectrometry on Its Tryptic Peptides Slide courtesy of Andrew Link
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Control Mix Lysates Identify and Quantify Proteins by Mass Spec Fractionate Proteins on SDS-PAGE Digest Bands with Trypsin Treatment 1Treatment 2 Protein Quantitation with Mass Spectrometry Bose et al., PNAS 103: 9773-8, 2006 Introduce Stable Isotope by Metabolic Labeling
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Studying EGFR Signal Transduction with Quantitative Proteomics Introduce Stable Isotope by Chemical Labeling Zhang et al., MCP 4: 1240-50, 2005
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Her2/neu and Breast Cancer 1987 – Southern blots of genomic DNA from breast cancer patients shows Her2 gene amplification. – Sample 3 & 4: normal level – Sample 1 & 2: 2-5 x normal – Sample 6 & 26: >5 x normal – Sample 18: > 20 x normal Correlation between Her2 gene copy number and patient survival Slamon, et al., Science 1987 100% Time (months) Patient Survival 80% 60% 40% 20% 0%
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Her2/neu and Breast Cancer Transgenic mice bearing the MMTV-Her2/neu construct develop breast cancer in all 5 pairs of mouse mammary glands. Tumor formation with Her2 in this tg model is more rapid than with the Myc oncogene. Muller et al., Cell 1988
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Drugs to Target Receptor Tyrosine Kinases HER2 EGFR HER2 HomodimerHeterodimer Extracellular domain Tyrosine- kinase domains Monoclonal Antibodies ATP-mimetic Tyrosine Kinase Inhibitors
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The RARα Nuclear Hormone Receptor in Acute Promyelocytic Leukemia (APL) APL has a characteristic translocation 15;17 that forms the PML-RARα fusion protein. Retinoic Acid (RA) binding converts PML-RARα from a transcriptional repressor to a transcriptional activator. All-trans retinoic acid (ATRA) has made APL the most treatable and best prognosis form of adult acute leukemia. PML Retinoic Acid Binding DNA Binding Retinoic Acid Receptor α ATRA
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GPCR signaling Controls Blood Pressure via the Renin-Angiotensin System Angiotensinogen Angiotensin I Angiotensin II Renin (kidney) ACE (lung) (Angiotensin Converting Enzyme) Angiotensin II Receptor (GPCR) T ACE inhibitors T Angiotensin Receptor Blockers Common Blood Pressure Medicines
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Erythropoietin (EPO) binds to a Cytokine Receptor Nucleus STAT5 DNA JAK2 Tyr Kinase EPO receptor Munugalavadla and Kapur, Reviews in Onc-Hem, 2005
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EPO Deficiency causes Anemia of Chronic Kidney Disease Chronic kidney disease causes a fall in EPO secretion and this results in decreased red blood cell production (i.e.- anemia). Therefore patients with chronic kidney disease are given recombinant EPO to prevent anemia. Kidney Bone Marrow Increased Red Blood Cell Production EPO
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Good Luck!
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