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Lactose Permease
From Proteopedia
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====Function of Lactose Permease==== | ====Function of Lactose Permease==== | ||
| - | [[Image:(image info)| | + | [[Image:(image info)|left|(Caption)]] Lactose Permease is a transmembrane protein that |
facilitates the passage of lactose across the phospholipid bi-layer of the cell membrane. The | facilitates the passage of lactose across the phospholipid bi-layer of the cell membrane. The | ||
transport mechanism used is an active co-transport that uses the inwardly directed H+ | transport mechanism used is an active co-transport that uses the inwardly directed H+ | ||
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the periplasm to the cytoplasm of the cell by an H+ proton.<ref name="A. Green, et. | the periplasm to the cytoplasm of the cell by an H+ proton.<ref name="A. Green, et. | ||
al.">[http://www.jbc.org/cgi/content/full/275/30/23240]</ref> | al.">[http://www.jbc.org/cgi/content/full/275/30/23240]</ref> | ||
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Lactose is a disaccharide carbohydrate found primarily in mammalian milk. It is a | Lactose is a disaccharide carbohydrate found primarily in mammalian milk. It is a | ||
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broken down into its monosaccharide subunits by the enzyme lactase so it may be used in the | broken down into its monosaccharide subunits by the enzyme lactase so it may be used in the | ||
process of cellular respiration.<ref name="Gita C. Gidwani">[http://www.faqs.org/nutrition/Kwa-Men/Lactose-Intolerance.html]<ref/> | process of cellular respiration.<ref name="Gita C. Gidwani">[http://www.faqs.org/nutrition/Kwa-Men/Lactose-Intolerance.html]<ref/> | ||
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====Structure of Lactose Permease==== | ====Structure of Lactose Permease==== | ||
| - | Lactose permease is a transmembrane protien consisting of N- and C- terminal domains, each | + | {{STRUCTURE_1pv7 | PDB=1pv7 | SCENE='Lactose_Permease/Beginning/1'}}Lactose permease is a transmembrane protien consisting of N- and C- terminal domains, each with <Scene> six transmembrane helices, symmetrically positioned within the permease. Six side chains have been determined to be irreplaceable with respect to active transport of |
| - | with <Scene> six transmembrane helices, symmetrically positioned within the permease. Six | + | |
| - | side chains have been determined to be irreplaceable with respect to active transport of | + | |
lactose. Those which are crucial for substrate binding are <Scene> Glu126, <Scene> Arg144, | lactose. Those which are crucial for substrate binding are <Scene> Glu126, <Scene> Arg144, | ||
and <Scene> Glu269, which may play a role in both substrate binding and proton translocation. | and <Scene> Glu269, which may play a role in both substrate binding and proton translocation. | ||
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and <Scene>Trp151, which are suspected to play an important role in the alignment of the | and <Scene>Trp151, which are suspected to play an important role in the alignment of the | ||
galactopyranosyl end of the substrate. | galactopyranosyl end of the substrate. | ||
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These sidechains can be found within the large internal <Scene>hydrophilic cavity of the | These sidechains can be found within the large internal <Scene>hydrophilic cavity of the | ||
protien. This is the active site where the substrate is recieved for transport. The | protien. This is the active site where the substrate is recieved for transport. The | ||
Revision as of 16:58, 14 January 2009
Function of Lactose Permease
Lactose Permease is a transmembrane protein thatfacilitates the passage of lactose across the phospholipid bi-layer of the cell membrane. The transport mechanism used is an active co-transport that uses the inwardly directed H+ electrochemical gradient as its driving force. As a result, the lactose is accompanied from the periplasm to the cytoplasm of the cell by an H+ proton.[1]
Lactose is a disaccharide carbohydrate found primarily in mammalian milk. It is a
disaccharide composed of the monosaccharides glucose and galactose. When lactose is ingested,
it is brought into cells in the digestive system by the protein Lactose Permease. Here it is
broken down into its monosaccharide subunits by the enzyme lactase so it may be used in the
process of cellular respiration.[2]
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