Lactose Permease

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	===Function of Lactose Permease===		===Function of Lactose Permease===
-	[[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 transport mechanism used is an active cotransport 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.	+	[[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 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 celll by an H+ proton.
-	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.	+
		+	Lactose is a disaccharide carbohydrate found primarily in mammalian milk. The disaccharide consists of the monosacharides glucose and galactose. When the lactose is ingested and absorbed into the cell, the enzyme lactase breaks the disaccharide into its monosaccharide subunits. These are in turn used in the cellular respiration process and broken down further into energy for the cell.
		+
	===Structure of Lactose Permease===		===Structure of Lactose Permease===
	<applet load="1PV7" size="300" color="white" frame="true" align="right" caption="Lactose Permease" />		<applet load="1PV7" size="300" color="white" frame="true" align="right" caption="Lactose Permease" />
-	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 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. <Scene>Arg302, <Scene>His322, and <Scene>Glu325 play essential roles in the proton translocation series of the co-transport. Two other important side chains are <scene>Cys148 and <Scene>Trp151, which are suspected to play an important role in the alignment of the galactopyranosyl end of the substrate.	+	Lactose permease is a transmembrane protein consisting of N- and C- terminal domains, each with six transmembrane helicies symmetrically positioned within the permease. There are six sidechains that play an irreplaceable role in the active transport of lactose through the protien. Three of these sidechains, Glutamic Acid 126, Arginine 144, and Glutamic Acid 269 have been shown to be crucial in substrate binding activities. Arginine 302, Histidine 322, and Glutamic Acid 325 are known to play a significant role in proton translocation(moving the H+ proton) throughout the transport process. Additionally, there are two residues that are suspected to play an important role in the alignment of the galactopyranosyl end of the substrate. These are Cysteine 148 and Tryptophan 151.
-	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 substrate, traditionally lactose, is shown <scene>here. Only the <Scene>inward-facing conformation, in which the large hydrophilic cavity discussed previously is oriented towards the cytoplasm, has been crystallized thus far.	+
-	Replace the PDB id after the STRUCTURE_ and after PDB= to load	+	These sidechains, which make up the active site of the protein, can be found within the large internal hydrophilic cavity of the lactose permease. It is here where the substrate is recieved for transport and it is the location from which it is deposited into the cell. The currently crystalized form of the permease is considered an 'inward-facing' conformation. This implies that the hydrophilic cavity mentioned previously is positioned with the opening towards the cytoplasm of the cell. Conversely, and outward-facing conformation would have the cavity facing the periplasm.
-	and display another structure.	+

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Revision as of 14:59, 15 January 2009

Function of Lactose Permease

Lactose Permease is a transmembrane protein that 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+ electrochemical gradient as its driving force. As a result, the lactose is accompanied from the periplasm to the cytoplasm of the celll by an H+ proton.

Lactose is a disaccharide carbohydrate found primarily in mammalian milk. The disaccharide consists of the monosacharides glucose and galactose. When the lactose is ingested and absorbed into the cell, the enzyme lactase breaks the disaccharide into its monosaccharide subunits. These are in turn used in the cellular respiration process and broken down further into energy for the cell.

Structure of Lactose Permease

spinqualitylabelsall models Lactose Permease Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Lactose permease is a transmembrane protein consisting of N- and C- terminal domains, each with six transmembrane helicies symmetrically positioned within the permease. There are six sidechains that play an irreplaceable role in the active transport of lactose through the protien. Three of these sidechains, Glutamic Acid 126, Arginine 144, and Glutamic Acid 269 have been shown to be crucial in substrate binding activities. Arginine 302, Histidine 322, and Glutamic Acid 325 are known to play a significant role in proton translocation(moving the H+ proton) throughout the transport process. Additionally, there are two residues that are suspected to play an important role in the alignment of the galactopyranosyl end of the substrate. These are Cysteine 148 and Tryptophan 151.

These sidechains, which make up the active site of the protein, can be found within the large internal hydrophilic cavity of the lactose permease. It is here where the substrate is recieved for transport and it is the location from which it is deposited into the cell. The currently crystalized form of the permease is considered an 'inward-facing' conformation. This implies that the hydrophilic cavity mentioned previously is positioned with the opening towards the cytoplasm of the cell. Conversely, and outward-facing conformation would have the cavity facing the periplasm.