Sandbox 177: Difference between revisions

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The N-terminus of CYPOR consists of a single alpha-helix composed of 25 amino acids that functions as a transmembrane anchor (~6kDa), holding the protein in the endoplasmic reticulum.<ref name="5TSON"/><ref name="10aTSON">PMID:18630181</ref> The remaining, soluble ~66kDa portion of the protein, responsible for reducing cytochrome P450, consists of three binding domains for the ligands involved in the electron transport chain.<ref name="5TSON"/> The FMN binding domain is composed of the first 170 residues of the soluble region, which are very similar to those of flavodoxin, another FMN binding protein.<ref name="5TSON"/> The FAD and NADPH binding domains are located closer to the C-terminus, and are very similar to the FAD domain in ferredoxin-NADP<sup>+</sup> oxidoreductase, both in terms of sequence and structure.<ref name="5TSON"/>

Between the FMN and FAD/NADPH bind domains is a connecting domain, which is a highly flexible random coil.<ref name="5TSON"/> The hinge region is composed of 12 residues from <scene name='Sandbox_177/Cyporhinge/4'>Gly232 to Arg243</scene>, and is highly conserved among most known CYPOR proteins, including those found in humans, rats and even yeast.<ref name="5TSON"/> For simplicity the hinge region has only been highlighted in the A chain (Fig 1), however it is present in all three chains. The hinge section is presumed to be responsible for the relatively increased mobility of the FMN domain, changes to conformation and the relative orientation of the binding domains.<ref name="5TSON"/> Studies that examined the rate of electron transfer within CYPOR seem to confirm this, as electron transfer rate appears to decrease proportionally to increases in the viscosity of the fluid medium it is in.<ref name="5TSON"/> Within the hinge, if residues are mutated or added (2-4 residues), the effect on electron transport is positive or negligible.<ref name="5TSON"/> However the same study found that the removal four residues from the hinge, as seen in Figure 1, prevents CYPOR from effectively transferring electrons to cytochrome P450, unless there is a high electron pool available.<ref name="5TSON"/> This indicates that without the hinge movement electrons are not able to be efficiently moved from FAD to FMN, decreasing the reductase capabilities of CYPOR.<ref name="5TSON"/>

Between the FMN and FAD/NADPH bind domains is a connecting domain, which is a highly flexible random coil.<ref name="5TSON"/> The hinge region is composed of 12 residues from <scene name='Sandbox_177/Cyporhinge/5'>Gly232 to Arg243</scene>, and is highly conserved among most known CYPOR proteins, including those found in humans, rats and even yeast.<ref name="5TSON"/> For simplicity the hinge region has only been highlighted in the A chain (Fig 1), however it is present in all three chains. The hinge section is presumed to be responsible for the relatively increased mobility of the FMN domain, changes to conformation and the relative orientation of the binding domains.<ref name="5TSON"/> Studies that examined the rate of electron transfer within CYPOR seem to confirm this, as electron transfer rate appears to decrease proportionally to increases in the viscosity of the fluid medium it is in.<ref name="5TSON"/> Within the hinge, if residues are mutated or added (2-4 residues), the effect on electron transport is positive or negligible.<ref name="5TSON"/> However the same study found that the removal four residues from the hinge, as seen in Figure 1, prevents CYPOR from effectively transferring electrons to cytochrome P450, unless there is a high electron pool available.<ref name="5TSON"/> This indicates that without the hinge movement electrons are not able to be efficiently moved from FAD to FMN, decreasing the reductase capabilities of CYPOR.<ref name="5TSON"/>

==='''Function'''===

Sandbox 177: Difference between revisions

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 The N-terminus of CYPOR consists of a single alpha-helix composed of 25 amino acids that functions as a transmembrane anchor (~6kDa), holding the protein in the endoplasmic reticulum.<ref name="5TSON"/><ref name="10aTSON">PMID:18630181</ref>  The remaining, soluble ~66kDa portion of the protein, responsible for reducing cytochrome P450, consists of three binding domains for the ligands involved in the electron transport chain.<ref name="5TSON"/>  The FMN binding domain is composed of the first 170 residues of the soluble region, which are very similar to those of flavodoxin, another FMN binding protein.<ref name="5TSON"/>  The FAD and NADPH binding domains are located closer to the C-terminus, and are very similar to the FAD domain in ferredoxin-NADP<sup>+</sup> oxidoreductase, both in terms of sequence and structure.<ref name="5TSON"/>
-Between the FMN and FAD/NADPH bind domains is a connecting domain, which is a highly flexible random coil.<ref name="5TSON"/>  The hinge region is composed of 12 residues from <scene name='Sandbox_177/Cyporhinge/4'>Gly232 to Arg243</scene>, and is highly conserved among most known CYPOR proteins, including those found in humans, rats and even yeast.<ref name="5TSON"/>  For simplicity the hinge region has only been highlighted in the A chain (Fig 1), however it is present in all three chains.  The hinge section is presumed to be responsible for the relatively increased mobility of the FMN domain, changes to conformation and the relative orientation of the binding domains.<ref name="5TSON"/>  Studies that examined the rate of electron transfer within CYPOR seem to confirm this, as electron transfer rate appears to decrease proportionally to increases in the viscosity of the fluid medium it is in.<ref name="5TSON"/> Within the hinge, if residues are mutated or added (2-4 residues), the effect on electron transport is positive or negligible.<ref name="5TSON"/>  However the same study found that the removal four residues from the hinge, as seen in Figure 1, prevents CYPOR from effectively transferring electrons to cytochrome P450, unless there is a high electron pool available.<ref name="5TSON"/>  This indicates that without the hinge movement electrons are not able to be efficiently moved from FAD to FMN, decreasing the reductase capabilities of CYPOR.<ref name="5TSON"/>
+Between the FMN and FAD/NADPH bind domains is a connecting domain, which is a highly flexible random coil.<ref name="5TSON"/>  The hinge region is composed of 12 residues from <scene name='Sandbox_177/Cyporhinge/5'>Gly232 to Arg243</scene>, and is highly conserved among most known CYPOR proteins, including those found in humans, rats and even yeast.<ref name="5TSON"/>  For simplicity the hinge region has only been highlighted in the A chain (Fig 1), however it is present in all three chains.  The hinge section is presumed to be responsible for the relatively increased mobility of the FMN domain, changes to conformation and the relative orientation of the binding domains.<ref name="5TSON"/>  Studies that examined the rate of electron transfer within CYPOR seem to confirm this, as electron transfer rate appears to decrease proportionally to increases in the viscosity of the fluid medium it is in.<ref name="5TSON"/> Within the hinge, if residues are mutated or added (2-4 residues), the effect on electron transport is positive or negligible.<ref name="5TSON"/>  However the same study found that the removal four residues from the hinge, as seen in Figure 1, prevents CYPOR from effectively transferring electrons to cytochrome P450, unless there is a high electron pool available.<ref name="5TSON"/>  This indicates that without the hinge movement electrons are not able to be efficiently moved from FAD to FMN, decreasing the reductase capabilities of CYPOR.<ref name="5TSON"/>
 ==='''Function'''===