Sandboxjg: Difference between revisions
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The CLC-ec1 transporter is a dimer formed of two polypeptide chains each containing an internal repeat arranged in an anti-parallel organization. Each monomer functions independently of the other and creates a passage for ions through the membrane. Its structure allows it to use electrostatic interactions with the dipoles of the α-helices and with nitrogen atoms and carboxyl groups in order to filter Cl- and H+ ions. Because each polypeptide chain functions independently, we will focus on the structure of one pore. | The CLC-ec1 transporter is a dimer formed of two polypeptide chains each containing an internal repeat arranged in an anti-parallel organization. Each monomer functions independently of the other and creates a passage for ions through the membrane. Its structure allows it to use electrostatic interactions with the dipoles of the α-helices and with nitrogen atoms and carboxyl groups in order to filter Cl- and H+ ions. Because each polypeptide chain functions independently, we will focus on the structure of one pore. | ||
There are 3 chloride binding sites in each monomer, an exterior binding site, a central binding site, and an interior binding site. These three sites span the membrane and define the transport pathway for Cl-. In the structure of the WT protein Glu 148 occupies either the central or the exterior binding sites where it likely competes with Cl- ions. Upon protonation the side chain of E148 extends towards the extracellular solution and opens the pathway allowing ion transport to occur. The H+ transport pathway in each monomer has two essential glutamate residues: one <scene name='Sandboxjg/Glu_148/1’>(Glu 148)</scene> functions as the coupling element between Cl- and H+ while the other <scene name='Sandboxjg/Glu_203/1’>(Glu 203)</scene>is involved in H+ permeation. | There are 3 chloride binding sites in each monomer, an exterior binding site, a central binding site, and an interior binding site. These three sites span the membrane and define the transport pathway for Cl-. In the structure of the WT protein Glu 148 occupies either the central or the exterior binding sites where it likely competes with Cl- ions. Upon protonation the side chain of E148 extends towards the extracellular solution and opens the pathway allowing ion transport to occur. The H+ transport pathway in each monomer has two essential glutamate residues: one <scene name='Sandboxjg/Glu_148/1’>(Glu 148)</scene> functions as the coupling element between Cl- and H+ while the other <scene name='Sandboxjg/Glu_203/1’>(Glu 203)</scene> is involved in H+ permeation. | ||
One of the interesting properties of this protein family is that its members can function either as ion channels or transporters. Furthermore, mutating Glu 148 to Ala in CLC-ec1 eliminates H+ transport but chloride ions can still move freely through the protein giving rise to a channel-like behavior. Mutations in other family members cause myotonia congenital (CLC-1), osteopetrosis (CLC-7) and kidney pathologies such as Bartter’s syndrome (CLC-Ka and -Kb) and Dent’s disease (CLC-5). | One of the interesting properties of this protein family is that its members can function either as ion channels or transporters. Furthermore, mutating Glu 148 to Ala in CLC-ec1 eliminates H+ transport but chloride ions can still move freely through the protein giving rise to a channel-like behavior. Mutations in other family members cause myotonia congenital (CLC-1), osteopetrosis (CLC-7) and kidney pathologies such as Bartter’s syndrome (CLC-Ka and -Kb) and Dent’s disease (CLC-5). | ||
To see the test <scene name='Sandboxjg/Test1ots/1'>click on me</scene> | To see the test <scene name='Sandboxjg/Test1ots/1'>click on me</scene> | ||
