PMID:12027015
| Citation |
Fu, D, Libson, A and Stroud, R (2002) The structure of GlpF, a glycerol conducting channel. Novartis Found. Symp. 245:51-61; discussion 61-5, 165-8 |
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| Abstract |
The passage of water or small neutral solutes across the cell membrane in animals, plants and bacteria is facilitated by a family of homologous membrane channels, variously known as aquaporins though perhaps more correctly as aquaglyceroporins. The glycerol facilitator (GlpF) is a 28 kDa aquaglyceroporin that catalyses transmembrane diffusion of glycerol and certain linear polyhydric alcohols in Escherichia coli. X-ray crystallographic analysis of GlpF to 2.2 A resolution revealed an alpha-barrel structure, surrounded by six full-length transmembrane helices and two half-spanning helices that are joined head-to-head in the middle of the membrane. These helices are arranged to a quasi twofold manner relative to the central membrane plane, where highly conserved residues make helix-to-helix contacts that stabilize the relative position and orientation of the helices in the structure. This sequence-structure correlation suggests that the evolutionary divergence of aquaporins and aquaglyceroporins is constrained by a conserved structural framework within which specialized function may be developed. Three glycerol molecules were resolved in the central channel through the GlpF monomer, thereby defining a transmembrane channel for glycerol permeation. The structure of glycerol GlpF complex provides insight into the chemical basis for transmembrane selective permeability. |
| Links | |
| Keywords |
Amino Acid Sequence; Aquaporins/chemistry; Conserved Sequence; Escherichia coli/physiology; Escherichia coli Proteins/chemistry; Glycerol; Models, Molecular; Protein Conformation; Protein Structure, Secondary |
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