341lecture18oct21sakai

341lecture18oct21sakai - Cell Biology 341 Last lecture:...

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Cell Biology 341 Weds., October 21, 2009 Today: Finish chapter 10 See the answers to selected questions at the end of the chapter posted on Sakai Begin Chapter 11 on transport across membranes Structures of transport proteins Active versus passive transport Last lecture: Transmembrane, lipid-anchored and peripheral membrane proteins are associated with a membrane in a specific orientation = asymmetrical property Hydrophobic R-groups contact the interior of the lipid bilayer Some transmembrane proteins form a pore composed of several α helices = channel proteins Porins are transmembrane β barrels Bacteriorhodopsin is a multipass transporter protein with 7 spans across the membrane Polar side chains on the interior of bacteriorhodopsin transport H + across the plasma membrane
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The cell cortex is a supporting network of fibrous proteins on the cytosolic face of the plasma membrane = cortical cytoskeleton Figure 10-41 the erythrocyte cortical cytoskeleton contains spectrin, along with actin filaments, linked to transmembrane proteins by attachment proteins. The cortex maintains the flattened shape of red blood cells. glycophorin These transmembrane proteins in “corrals” do not diffuse in the membrane these are peripheral proteins
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Cells can restrict the movement of proteins to localized membrane domains Membrane proteins may be tethered to the underlying cell cortex or to molecules of the extracellular matrix (see fig 10-39) In epithelial cells lining the gut, transport proteins (A)
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This note was uploaded on 12/05/2009 for the course BIO 341 taught by Professor Noris during the Fall '09 term at Rhode Island.

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341lecture18oct21sakai - Cell Biology 341 Last lecture:...

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