BIO130H1 Lecture 8: Membrane Proteins & Transport Across Membranes
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BIO130H1 Full Course Notes
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Integral membrane proteins can penetrate or span the lipid bilayer. Integral membrane proteins destroy membrane with detergents to extract the protein: for studying the properties of integral membrane proteins: Lateral diffusion within leaflet: no flip-flop, frap: fluorescence recovery after photobleaching, 1. Photobleach spot with laser beam: destroy fluorescent proteins, 3. Recovery: measure how long it takes for neighbouring proteins to move into photobleached area, faster to recover faster the proteins more fluid. Large uncharged polar molecules: sucrose; glucose is slightly permeable. Ions: na+, h+, k+, ca2: require membrane proteins for transport, proteins involved in membrane transport, multipass transmembrane proteins, create a protein-lined path across cell membrane, transport polar and charged molecules. Passive transport: channel proteins, hydrophilic pore across membrane, most channel proteins are selective, e. g. ion channels transport a specific ion, passive transport, weak interaction with solute, faster transport by channels than transporters, several molecules pass through when open.