User:Giselle Flores/Sandbox 1

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=== GPIHBP1 ===
=== GPIHBP1 ===
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Glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 ([https://en.wikipedia.org/wiki/GPIHBP1 GPIHBP1]) is a secondary domain that is critical to the stabilization, function, and movement of <scene name='87/877513/Original_scene/1'>LPL</scene>.<ref name=”Birrane”>PMID:30559189</ref> The GPIHBP1’s highly acidic and intrinsically disordered N-terminal domain are essential to the binding of LPL’s C-terminal Domain. It has been shown that GPIHBP1 has a “three fingered domain”, which holds it tightly to LPL by <scene name='87/877513/Hydrophobic_interface-labeled/3'>hydrophobic interactions</scene>.<ref name=”Birrane”>PMID:30559189</ref> The importance of GPIBP1’s affinity to LPL was analyzed by Birrane et al.<ref name=”Birrane”>PMID:30559189</ref>, and it was found that missense mutations of critical residues resulted in high amounts of impairments. It was also concluded that these impairments caused hypertriglyceridemia (chylomicronemia).<ref name=”Birrane”>PMID:30559189</ref>
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Glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 ([https://en.wikipedia.org/wiki/GPIHBP1 GPIHBP1]) is a secondary domain that is critical to the stabilization, function, and movement of <scene name='87/877513/Original_scene/1'>LPL</scene>.<ref name=”Birrane”>PMID:30559189</ref> The GPIHBP1’s highly acidic and intrinsically disordered N-terminal domain are essential to the binding of LPL’s C-terminal Domain. It has been shown that GPIHBP1 has a “three-fingered domain”, which holds it tightly to LPL by <scene name='87/877513/Hydrophobic_interface-labeled/3'>hydrophobic interactions</scene>.<ref name=”Birrane”>PMID:30559189</ref> The importance of GPIBP1’s affinity to LPL was analyzed by Birrane et al.<ref name=”Birrane”>PMID:30559189</ref>, and it was found that missense mutations of critical residues resulted in high amounts of impairments. It was also concluded that these impairments caused hypertriglyceridemia (chylomicronemia).<ref name=”Birrane”>PMID:30559189</ref>
== Structural Highlights ==
== Structural Highlights ==
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=== Lid and Lipid Binding Region ===
=== Lid and Lipid Binding Region ===
In the presence of the GPIHBP1 inhibitor, the <scene name='87/877513/Lid_region_final/2'>lid region</scene> and <scene name='87/877516/Inhibitorsbound/1'>lipid-binding region</scene> become visible within the structure. As displayed through a study conducted by Arora et. al, in 2019, the lipid-binding region of LPL actively interacts with the known inhibitor in the heterodimeric form. <ref name=”Arora”>PMID:31072929</ref> This was established to be the only time that the heterodimeric form was shown as an active lipase. The lid region residues Ile245, Ile249, V251, Ile252, Leu257, Val260, Leu263, and Val264, are found as an open conformation which is composed of two small alpha helices that reach out and away from the protein. The lid and lipid-binding region create hydrophobic patches on the surface of lipoprotein lipase which are essential for <scene name='87/877513/Lipid_binding_and_lid/1'>ligand binding</scene> by LPL.
In the presence of the GPIHBP1 inhibitor, the <scene name='87/877513/Lid_region_final/2'>lid region</scene> and <scene name='87/877516/Inhibitorsbound/1'>lipid-binding region</scene> become visible within the structure. As displayed through a study conducted by Arora et. al, in 2019, the lipid-binding region of LPL actively interacts with the known inhibitor in the heterodimeric form. <ref name=”Arora”>PMID:31072929</ref> This was established to be the only time that the heterodimeric form was shown as an active lipase. The lid region residues Ile245, Ile249, V251, Ile252, Leu257, Val260, Leu263, and Val264, are found as an open conformation which is composed of two small alpha helices that reach out and away from the protein. The lid and lipid-binding region create hydrophobic patches on the surface of lipoprotein lipase which are essential for <scene name='87/877513/Lipid_binding_and_lid/1'>ligand binding</scene> by LPL.
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[[Image:Inhibiting.png|300 px|right|thumb|The novel inhibitor bound between the lipid-binding region of one LPL and the catalytic site of the other LPL of the tetramer.]]
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==Mechanism==
==Mechanism==
Lipoprotein Lipase functions to catalyze the hydrolysis of one [https://en.wikipedia.org/wiki/Ester ester bond] of triglycerides in order to remove one fatty acid tail and turn the triglyceride into a diglyceride. It does this by utilizing a simple [https://en.wikipedia.org/wiki/Serine_hydrolase serine hydrolase] mechanism, in which it uses a <scene name='87/877513/Catalytic_triad-1/6'>catalytic triad</scene> composed of Asp183, His268, and Ser159 to catalyze the hydrolysis. His268 serves as a base catalyst by deprotonation of Ser159, which can then serve as the [https://en.wikipedia.org/wiki/Nucleophile nucleophile] to attack the carbonyl carbon of one of the fatty acid chains of a triglyceride. This forms a tetrahedral intermediate, which is stabilized by the amide of Trp82 and Leu160 residues, called the <scene name='87/877513/Oxyanion_hole_-_labeled/8'>oxyanion hole</scene>. The single fatty acid chain is cleaved from the triglyceride, forming the diglyceride product. Then, water is used to free the fatty acid from Ser159 and return all of the residues back to their starting point, in order to perform the mechanism again on another triglyceride. Ultimately, the hydrolysis results in the formation of one free fatty acid and glycerol with two fatty acid tails (Figure 2).
Lipoprotein Lipase functions to catalyze the hydrolysis of one [https://en.wikipedia.org/wiki/Ester ester bond] of triglycerides in order to remove one fatty acid tail and turn the triglyceride into a diglyceride. It does this by utilizing a simple [https://en.wikipedia.org/wiki/Serine_hydrolase serine hydrolase] mechanism, in which it uses a <scene name='87/877513/Catalytic_triad-1/6'>catalytic triad</scene> composed of Asp183, His268, and Ser159 to catalyze the hydrolysis. His268 serves as a base catalyst by deprotonation of Ser159, which can then serve as the [https://en.wikipedia.org/wiki/Nucleophile nucleophile] to attack the carbonyl carbon of one of the fatty acid chains of a triglyceride. This forms a tetrahedral intermediate, which is stabilized by the amide of Trp82 and Leu160 residues, called the <scene name='87/877513/Oxyanion_hole_-_labeled/8'>oxyanion hole</scene>. The single fatty acid chain is cleaved from the triglyceride, forming the diglyceride product. Then, water is used to free the fatty acid from Ser159 and return all of the residues back to their starting point, in order to perform the mechanism again on another triglyceride. Ultimately, the hydrolysis results in the formation of one free fatty acid and glycerol with two fatty acid tails (Figure 2).

Revision as of 02:29, 28 April 2021

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