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Sec61/SecY Protein review

Sec61/SecY Protein review. Sec61 protein is important for the movement of proteins across the cell membrane? A signal sequence guides the protein to the Sec61 protein? A plug model was put into play by this paper?. Lipid Membrane. More characteristics.

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Sec61/SecY Protein review

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  1. Sec61/SecY Protein review • Sec61 protein is important for the movement of proteins across the cell membrane? • A signal sequence guides the protein to the Sec61 protein? • A plug model was put into play by this paper?

  2. Lipid Membrane

  3. More characteristics • Driving Force of formation of lipid bilayer are Hydrophobic Interactions

  4. Kinds of lipids in membrane • Phospholipids • Glycolipids • cholesterol

  5. Phospholipids • PE- phosphatidyl ethanolamine • PC- phosphatidyl choline • SM- sphingomyleine • PS- phosphatidyl serine Can serve as different markers for cell

  6. Kyte Dolittle

  7. K+ Channel • Selective filter for moving potassium out of the cell • Has four identical transmembrane subunits • Each subunit has 2 transmembrane helices and a third shorter helix called the pore helix • These subunits form a central pore

  8. K+ channel

  9. Channel tilts outwards • Has a loop that forms in channel and is going to make the selectivity filter, which will only allow K+ out • Filter formed by carbonyl oxygens of the peptide backbone

  10. K+ is 1.95 A NA+ is 0.95 A • In the cell potassium will be hydrated with water and so will sodium • Bonding between these elements and water will be a specific length • Water needs to be shed in order for K+ to go through

  11. Carbonyl oxygen will act as the surrogate water • The dehydration of the ion takes energy but it is immediately made up by interactions with carbonyl oxygen • Na is too small for this mechanism and therefore is not transported out

  12. Porin • Made by up and down barrel • Either 16 are 18 beta strands make up the porin • Porin channel has a loop region in the middle of it which will act as a selective filter. 8 A in diameter • Only certain small molecules will be able to transverse the membrane

  13. Porin is made up of three channels as described

  14. Bacteriarhodopsin • 7 transmembrane alpha helices • This protein is used for transforming light to chemical energy • Proton pump

  15. Retinol • Bound in the pocket of the protein • Undergoes isomerization when light hits it from trans to cis • Bound covalently to lysine 216

  16. The mechanism

  17. Light at a certain wavelength cause change from trans to cis of retinal • Then Asp transfers proton to schiff base • This proton is then transferred to Asp 85 and then out to the extracellular space

  18. Result • Form an electrochemical gradient which is important for bacteria survival • Use for generation of energy

  19. Photosynthetic Reaction Center • L, H, M and cytochrome subunits • L and M subunits each have 5 hydrophobic transmembrane helices • H subunit has one transmembrane helice

  20. What is taking place • Transfer of light to generate energy • Players in the reaction must be arranged in a way that ensures the forward movement of the reaction • Photons absorbed by chlorophylls

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