Lecture 2--membranes

Want to look at protein that was originally there not

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Unformatted text preview: as originally there, not new protein because that can be inserted anywhere on the membrane M H M/H human/mouse made a human/ mouse hybrid human and mouse have differenc eproteins on the surface; if proteins ar estatic: what do you predict will happen if you fuse cells together? is would only be on one half; they wouldnt mix how do you follow the proteins in the heterokaryon? could use amino fluorescence anitobody directed against human antigen, another antibody against the mouse; they would be associated with different colors; if they are mixing, then the colors should overlap. ex: green + red = yellow Temperature affects the fluidity of the lipid bilayer changes with time: fish moving from top of water to bottom change composition of cells to not freeze Above the transition temperature, the molecules of the unsaturated lipids have a kink in their fatty acid lipid bilayer are free to move. chains to this makes the membrane more fluid and can change the transition temperature Below the transition temperature, the movement of molecules is reduced and restricted. membranes that consists of ddifferen lipids will ahve different transition temprature; and depending on the heterogeneity of the lipds will be the s harpness of the transition tempersture if you have many different lipids with different transition temperatures, then temperature wshouldnt be as sharp as the one with the ame lipid Membranes contain many associated proteins and carbohydrates the inside of the lumen of ER is topologically equvalent to the outside of the cell lipids are heterogeneous; protein span membrane. portions of proteins outside the c ell is modified by cabs. never on c ytoplasmic side of cells Singer and Nicolson model 1972 Proteins can be associated with membranes in several different ways • Transmembrane proteins pass all the way through membrane • Peripheral proteins • Lipidthe membrane but not encopass it, - anchored proteins touch they interact with the interal protein. outside the membrane, c ovalently attahed to the lipid, and it wants to go inside the c ell Integral membrane proteins can be recognized from their amino acid sequences Transmembrane domains are often alpha helices consisting of hydrophobic amino acid residues Regions of hydrophobicity can be visualize in a Kyte-Doolittle plot plot reveals transmembrane domain. odr 10 is a worm protein that s a receptor for a odorant callded diafitil, smells like movie theater popcorn odr 10 was clones. take sequence and out into plot, is the seuence of aa N-C terminal put into little groups, and for each of those groups they are given a sore for howhydrophobic they are or hydrophilic(negative) does it have anyhydrophobic patches, adding up hydrophobic patches, there are 7 , and they are alpha helixes Proteins can be modified with fatty acids in several ways Lipid modifications regulate cell signaling by targeting intracellular proteins to cell membrane inner or outer leaflet of a membrane 16 An experimental approach for deducing the nature of protein association with plasma membrane How are proteins associated with red blood cell membranes? Studying proteins of the plasma membrane S...
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