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Structure and dynamics of polypeptides and proteins in lipid membranes
Published online by Cambridge University Press: 17 March 2009
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The elucidation of the molecular mechanisms whereby ions and polar molecules are translocated across the hydrophobic barrier of a lipid bilayer in biological membranes is one of the most challenging problems in biological research. Specific membrane proteins, such as pumps, carriers and channels, play the central role in the various translocation pathways. Recent progress in expression cloning has provided the sequence of a number of biologically important membrane proteins and in principle the door is open to investigate every protein which might be of importance in the central signal transduction and transport processes. Unfortunately, to date there are only a few examples where the three-dimensional structure of membrane proteins are known at atomic resolution. The photosynthetic reaction centres from purple bacteria (Deisenhofer et al. 1985), bacteriorhodopsin (Henderson et al. 1990) and the large porin channel of Rhodobacter capsulata (Weiss et al. 1991). According to these structural data membrane proteins seem to fold in general in membrane-spanning α-helices and β-strands in order to saturate hydrogen bonds. Only these two motifs seem to form stable structures which can be in contact with the hydrophobic lipid interior of a membrane.
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- Copyright © Cambridge University Press 1992
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