User:Laura Fountain/Chloride Ion Channel: Difference between revisions
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{{STRUCTURE_1k0o | PDB=1k0o | SCENE=User:Laura_Fountain/Sandbox_1/1k0o/1}} | |||
== CLIC1: A Chloride Ion Channel == | == CLIC1: A Chloride Ion Channel == | ||
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This wide range of locations in the cell causes a plausible reason to assume that the CLIC chloride channel family participate in an equally wide variety of physiological processes. Some of these include cell division, kidney function, bone resorption, transepithelial transport, and signal transduction. <ref name="Cromer">PMID:12202911</ref> | This wide range of locations in the cell causes a plausible reason to assume that the CLIC chloride channel family participate in an equally wide variety of physiological processes. Some of these include cell division, kidney function, bone resorption, transepithelial transport, and signal transduction. <ref name="Cromer">PMID:12202911</ref> | ||
CLIC1 is a member of the highly conserved class of chloride ion channels that exist in both soluble and integral membrane forms. When disrupted cells are washed approximately half of the CLIC1 proteins will remain within the fractioned membrane as would be expected from an integral membrane protein. Atypically, the other half will behave as a soluble cytoplasmic protein and exist within the aqueous extract.<ref name="Tulk">PMID:11940526</ref> | CLIC1 is a member of the highly conserved class of chloride ion channels that exist in both soluble and integral membrane forms. When disrupted cells are washed approximately half of the CLIC1 proteins will remain within the fractioned membrane as would be expected from an integral membrane protein. Atypically, the other half will behave as a soluble cytoplasmic protein and exist within the aqueous extract.<ref name="Tulk">PMID:11940526</ref> Tulk et. al. showed that functionality of the protein isn't greatly effected by the method with which the protein inserts itself into the membrane. | ||
This is part of the evidence which leads Tulk et. al. to postulate that CLIC1 is among the small group of proteins which are assembled as soluble cytoplasmic proteins, which will then insert themselves into the appropriate membrane via their own mechanism. | This is part of the evidence which leads Tulk et. al. to postulate that CLIC1 is among the small group of proteins which are assembled as soluble cytoplasmic proteins, which will then insert themselves into the appropriate membrane via their own mechanism. | ||
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== Structure == | == Structure == | ||
<applet load='1k0o' size='300' frame='true' align='right' caption=' | <applet load='1k0o' size='300' frame='true' align='right' caption='Dimer view of CLIC1' /> | ||
The CLIC family is defined by a COOH-terminal core segment of ~230 amino acids that are highly conserved among the family members. CLIC1 only contains a few amino acids upstream of the conserved core.<ref name="Tulk">PMID:11940526</ref> | The CLIC family is defined by a COOH-terminal core segment of ~230 amino acids that are highly conserved among the family members. CLIC1 only contains a few amino acids upstream of the <scene name='User:Laura_Fountain/Sandbox_1/1k0o/3'>conserved core</scene>.<ref name="Tulk">PMID:11940526</ref> | ||
The N-domain of CLIC1 (1-90) consists of 4 beta-sheets and 3 alpha-helices and the C-domain consists entirely of alpha-helices. The long loop between helices | It has a homodimeric structure with one pore per subunit, which creates an incredibly unique "double barreled" channel. The <scene name='User:Laura_Fountain/Sandbox_1/1k0o/4'>N-domain</scene> of CLIC1 (1-90) consists of <scene name='User:Laura_Fountain/Sandbox_1/1k0o/5'>4 beta-sheets</scene> and <scene name='User:Laura_Fountain/Sandbox_1/1k0o/6'>3 alpha-helices</scene>, and the <scene name='User:Laura_Fountain/Sandbox_1/1k0o/7'>C-domain</scene> consists entirely of alpha-helices. The long loop between helices at the foot of CLIC1 (Pro147–Gln164) is a distinctive feature of the CLICs. It is highly negatively charged with seven acidic residues between Pro149 and Glu160<ref name="Harrop">PMID:11551966</ref> | ||
(Pro147–Gln164) is a distinctive feature of the CLICs. It is highly negatively charged with seven acidic residues between Pro149 and Glu160<ref name="Harrop">PMID:11551966 | |||
Integration of CLIC1 into the membrane is a highly prospect mechanism, but it is likely to require a major structural rearrangement, probably of the N-domain<ref name="Harrop">PMID:11551966</ref> (residues 1-90), which would insert itself and then allow the C-domain helices to insert and form the pore. | |||
== Selectivity for Chloride == | == Selectivity for Chloride == | ||
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== Potential Ion Gating == | == Potential Ion Gating == | ||
At its binding site in the pore, chloride interacts with the ends of four helices that come from both sides of the membrane. A | At its binding site in the pore, chloride interacts with the ends of four helices that come from both sides of the membrane. A glutamate residue that protrudes into the pore is proposed to participate in gating.<ref name="CLC">PMID:12163078</ref> | ||
== References == | == References == | ||
<references/> | <references/> | ||
