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Lecture 2--membranes

Activation of the insulin receptor leads to

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Unformatted text preview: allowing import of glucose The plasma membrane is organized into domains r=proteins like to c ongregate andpolymerize they can be congregated because they are attched to things inside the cell (cytoskeleton) that keeo them there; possible that something on outside, the extracellular matrix organizes them or two scels interacting with echtoher will ahve priteins localizing there epithelial cells divided int o compartment; the rop is apical , basolateral c ompartment, both s eparated by eachother by tight junctions; barriers of diffusion by these proteins Distribution of proteins within the plasma membrane can change to accommodate the functional demands of the cell Proteins move within the lipid bilayer Depending on the cell type, the specific protein and environmental conditions, integral membrane proteins can exhibit several types of mobility. E: fenced in (tight junctions) D: form aggregates C attache dto cytoskeleton so restricted in movement B not moving at all A moves randomly The structure of the plasma membrane consists of discrete microdomains that segregate functions into subcompartments lipids are in domains too non different sizes and can be overlapping (extensively) yeast cell microdomains Both lipids and proteins are segregated into microdomains Cholesterol- and sphingolipid-rich lipid “rafts” are microdomains that are thought to concentrate signaling proteins membrane fatter From “the inner life of the cell” Surveying membrane localization in yeast Tagged Proteins from paper: looks like almost every protein is in a micro domain; none of them seem to be homogeneously s pread out in number; Lipid reporters Most, if not all, proteins localize in non-uniform patches of cell membranes Patchwork organization of the yeast plasma membrane into numerous coexisting domains. Spira F, Mueller NS, Beck G, von Olshausen P, Beig J, Wedlich-Söldner R. Nat Cell Biol. 2012 Apr 29;14(6):640-8. FRAP-Fluorescence Recovery After Photobleaching A method for measuring protein movement within plasma membranes if protein moves into affected area then it can be seen because fluorescence will c ome back to the bleached area fluorescent proteins can be bleached. fluorescent proteins are excited by light, y ou can add so much light that you kill flourescence and bleaches it What factors regulate protein diffusion in the endoplasmic reticulum? Is diffusibility affected by folding status? Is diffusibility affected by sugar modifications? how much are the proteins and lipids moving around within their microdomain in relatio to eachtoher frap: all proteins that co go to plasma membrane are inserted in ``ER first, helps them fold, modification, and then move through. how fast do these proteins move through ER what features of proteins slow them down or affect their diffusion to the ER 1. folding status: in ER protein folded into 3D s hape, if that doesnt happen does that slow the proteins from moving through the ER? 2. is their diffusibility affected by their sugar molecules or glycosilations. Nehls et...
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