Lactose Permease: Difference between revisions

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.

<scene name='Lactose_Permease/Beginning/1'>Lactose permease</scene> is a transmembrane protein consisting of N- and C- terminal domains (depicted in this model by the blue and red hemispheres), each with six <scene name='Lactose_Permease/Backbone/3'>transmembrane helices</scene> symmetrically positioned within the permease.  There are six sidechains that play an irreplaceable role in the active transport of lactose through the protein.  Three of these sidechains, <scene name='Lactose_Permease/Glu126/3'>Glutamic Acid 126</scene>, <scene name='Lactose_Permease/Arg144/3'>Arginine 144</scene>, and <scene name='Lactose_Permease/Glu269/3'>Glutamic Acid 269</scene> have been shown to be crucial in substrate binding activities.  <scene name='Lactose_Permease/Arg302/2'>Arginine 302</scene>, <scene name='Lactose_Permease/His322/2'>Histidine 322</scene>, and <scene name='Lactose_Permease/Glu325/2'>Glutamic Acid 325</scene> 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 <scene name='Lactose_Permease/Cys148/2'>Cysteine 148</scene> and <scene name='Lactose_Permease/Trp151/2'>Tryptophan 151</scene>.