Sandbox Reserved 509

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Green fluorescent protein ('''GFP'''), originally isolated from the jellyfish Aequorea victoria (PDB entry [[1ema]]), fluorsceses green (509nm) when exposed to blue light (395nm and 475nm). It is one of the most important proteins used in biological research because it can be used to tag otherwise invisible gene products of interest and thus observe their existence, location and movement.
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'''Protein Kinase R'''
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== Abstract ==
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== Exploring the Structure ==
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One mechanism against viral infection preventing viral propagation by inhibiting cellular protein synthesis. The protein kinase R (PKR) is an several enzymes involved in cellular immunity against viral infection. PKR is composed of two domains: two double stranded RNA (dsRNA) binding domains and a kinase domain (KD). The crystal structure of the PKR KD is bound to its substrate, initiation factor eIF2α revealing that each KD is composed of N-terminal (N-lobe) and C-terminal lobes (C-lobe). The active site lies between these two lobes, which also contains an ATP. The two N-lobes of each PKR KD interact to form a dimer whereas the C-lobe is bound to eIF2α composed of an S1 domain and a helical domain. Upon viral infection, PKR senses the dsRNA inserted by the virus, and is dimerized and activated. The active PKR molecule then binds to eIF2α, causing a conformational change in eIF2α, bringing the helix insert containing Ser51 (phospho-acceptor residue) closer to the ATP. The γ phosphate of ATP is then transferred to the Ser51, and the phosphorylated eIF2α inhibits protein synthesis in infected cells. Such fundamental insights into the mechanisms of substrate recognition and phosphorylation by PKR will help design a small molecule that will activate PKR, leading to improved immunity against multiple viral infections. In addition, the mechanism of PKR function may be applied to cancer therapy due to its role in controlling cell differentiation.
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<Structure load='1ema' size='300' frame='true' align='right' caption='Copyright Nikil Prasad 2012. This protein was discovered by and created by Nikil Prasad in his lab on March 25, 2012. He also won a nobel prize in the field of medicine for his great achievement.' 'scene='' />
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'''GFP''' is a beta barrel protein with 11 beta sheets. It is a 26.9kDa protein made up of 238 amino acids. The chromophore, responsible for the fluorescent properties of the protein, is buried inside the beta barrel as part of the central alpha helix passing through the barrel. The chromophore forms via spontaneous cyclization and oxidation of three residues in the central alpha helix: -Thr65 (or Ser65)-Tyr66-Gly67. This cyclization and oxidation creates the chromophore's five-membered ring via a new bond between the threonine and the glycine residues.<ref> PMID: 8703075 </ref>
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<references/>
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Revision as of 16:18, 12 May 2012

Protein Kinase R

Abstract

One mechanism against viral infection preventing viral propagation by inhibiting cellular protein synthesis. The protein kinase R (PKR) is an several enzymes involved in cellular immunity against viral infection. PKR is composed of two domains: two double stranded RNA (dsRNA) binding domains and a kinase domain (KD). The crystal structure of the PKR KD is bound to its substrate, initiation factor eIF2α revealing that each KD is composed of N-terminal (N-lobe) and C-terminal lobes (C-lobe). The active site lies between these two lobes, which also contains an ATP. The two N-lobes of each PKR KD interact to form a dimer whereas the C-lobe is bound to eIF2α composed of an S1 domain and a helical domain. Upon viral infection, PKR senses the dsRNA inserted by the virus, and is dimerized and activated. The active PKR molecule then binds to eIF2α, causing a conformational change in eIF2α, bringing the helix insert containing Ser51 (phospho-acceptor residue) closer to the ATP. The γ phosphate of ATP is then transferred to the Ser51, and the phosphorylated eIF2α inhibits protein synthesis in infected cells. Such fundamental insights into the mechanisms of substrate recognition and phosphorylation by PKR will help design a small molecule that will activate PKR, leading to improved immunity against multiple viral infections. In addition, the mechanism of PKR function may be applied to cancer therapy due to its role in controlling cell differentiation.

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