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THE TRANSPORTER

THE TRANSPORTER. ( TARGET FOR DRUG ACTION ). Heny Ekowati PHARMACY DEPARTMENT MEDICINE AND HEALTH SCIENCES FACULTY UNIVERSITY OF JENDERAL SOEDIRMAN 2013 . Membrane protein transporter types. Channels facilitate diffusion through an aqueous pore when a conformational

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THE TRANSPORTER

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  1. THE TRANSPORTER ( TARGET FOR DRUG ACTION ) Heny Ekowati PHARMACY DEPARTMENT MEDICINE AND HEALTH SCIENCES FACULTY UNIVERSITY OF JENDERAL SOEDIRMAN 2013

  2. Membrane protein transporter types Channels facilitate diffusion through an aqueous pore when a conformational change opens a gate Some carrier types facilitate diffusion, others use energy to pump molecules against Their gradient. They must bind the solute to initiate a conformational change

  3. The membrane lipid barrier:Passive diffusion through the lipid bilayer • Concentration gradient up, diffusion up • Molecule lipid solubility up, diffusion up • Molecular size up, diffusion down • Molecule electrically charged, diffusion blocked

  4. Specialized membrane proteins transport molecules across membranes • Simple diffusion • Species of molecule limited by membrane physics • Rate is slow and linearly related to concentration gradient • Membrane transport • Overall not limited by size, charge, or hydrophilia • Is highly selective for specific needed molecules • Rate is fast and not linear

  5. Carrier types • Uniporter- transports only one molecule species • Symporter- coupled transport of 2 different molecular species in the same direction • Antiporter- coupled transport of 2 different molecular species in the opposite direction • Symporters & antiporters are usually pumps • Some types transport more than one molecule of a species/cycle

  6. The glucose uniporter transports glucose across membranes • Ligand (glucose) binding flips the transporter to a different conformation (changes shape) • The new conformation releases glucose on the other side of the membrane • Release allows it to flip back to repeat the cycle

  7. Band 3 facilitated diffusion anion antiporter in red blood cells • Multipass protein that binds to spectrin • Exchanges Cl- for HCO3- • Important for transporting CO2 to the lungs

  8. Band 3 facilitated diffusion anion antiporter in red blood cells • When the bicarbonate diffusion gradient is reversed, the process reverses

  9. Band 3 function in RBCs

  10. Primary active transport example:The Na+- K+ antiporter pump • Pumps 3 Na+ ions out of cell & 2 K+ ions in • Maintains Na+ & K+ cell membrane gradients • Each cycle uses one ATP, 100 cycles/sec • Uses ¼ energy of most cells, ¾ for neurons

  11. The Na+ - K+ pump cycle

  12. Secondary active transport example: The sodium-glucose symporter pump • Gradients from primary pumps power secondary active transport • Different types, can be antiporters or symporters • Pictured, the Na+ gradient powers conformational change • Glucose is pumped in against its gradient

  13. Retrieval of GI tract glucose by enterocytes

  14. THE NEPHRON

  15. THE NEPHRON Glomerulus Bowman’s capsule prox. conv. tubule Loop (ansa) of Henle:descend. limb, arcus, ascend. limb dist. conv. tubule collect. tubule

  16. Simport: Na+/Cl-

  17. Simport Na+/K+2Cl-

  18. Uniport GABA

  19. Na+/K+ ATPase

  20. H+/K+-ATPase

  21. TERIMA KASIH

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