Primary sequence can be used to predict the presence

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Unformatted text preview: rane segments is referred to as the topology of the membrane protein. Glycophorin in red blood cells Extensive glycosylaEon Specific orientaWon in membrane: N to C terminus (asymmetry) Single transmembrane helix Hydrophilic protein domains Bacteriorhodopsin, 7 transmembrane helices Light energy H+ H+ Higher ConcentraWon H+ Membrane Lower ConcentraWon H+ Membrane spanning domains Pump protons across the plasma membrane of halophilic bacteria Extracellular regions Bacteriorhodopsin, Sequence analysis Which residues are in contact with the hydrophobic core ­ those highlighted in yellow or those highlighted in red? Primary sequence can be used to predict the presence of a transmembrane helix ΔG < 0 → transfer from membrane to water is favorable Using the primary sequence the presence of a transmembrane helix glycophorin A •  Membrane spanning helices are generally 20 amino acids in length. Therefore a window is a stretch of 20 amino acids •  A window above the criterion line suggests (but does not prove) the presence of a transmembrane helix. of 20 residues Hydropathy plot for Bacteriorhodopsin 7 regions of high hydropathy correspond to the 7 transmembrane helices Transmembrane β ­sheets β ­strand: 3.5 Å distance between Cα posiEons Transmembrane β...
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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