Sandbox 3

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[[Image:3cl0_1.png|thumb|left|150px|Influenza neuraminidase (3cl0)]]
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[[Image:1ema.gif|thumb|left|350px|Green fluorescent protein (1ema)]]
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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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'''Influenza neuraminidase''' is a glycoprotein in the influenza virus membrane. Before an infected cell can release the virus into its surroundings to infect new cells, neuraminidase must cleave sialic acid from both virus and cellular glycoproteins.
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== Exploring the Structure ==
== Exploring the Structure ==
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<applet load='3cl0' size='300' frame='true' align='right' caption='Insert caption here' />
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<applet load='1ema' size='300' frame='true' align='right' caption='Insert caption here' />
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Because of its important role in virus infectivity, several anti-viral drugs have been designed to target neuraminidase, including oseltamivir (Tamiflu) and zanamivir (Relenza). Oseltamavir binding to neuraminidase moves glutamate 276 towards histidine 274, making more room for oseltamavir to bind tightly (PDB entry [[2hu4]]). But, in a <scene name='Sandbox_3/H274y/2'>common mutant</scene> (H274Y), a larger tyrosine replaces the smaller histidine 274, preventing glutamate 276 from moving to make room for oseltamavir binding, resulting in weaker drug binding and thus resistance (PDB entry [[3cl0]]). Luckily the H274Y neuraminidase mutant is still susceptible to zanamivir, which is smaller than oseltamavir.<ref>PMID:18480754</ref>
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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 <scene name='Sandbox_3/1ema_chromophore/1'>chromophore</scene>, 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>
<references/>
<references/>
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==Quiz==
==Quiz==
<quiz display=simple>
<quiz display=simple>
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{Which residue moves to make room for Tamiflu binding but cannot do so in the H274Y neuraminidase mutant?
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{How many alpha helices are in this structure?}
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|type="[]"}
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- One
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- histidine 274
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- None
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- serine 278
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+ Eleven
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+ glutamate 276
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- Twelve
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- tyrosine 274
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</quiz>
</quiz>

Revision as of 12:59, 13 November 2010

Green fluorescent protein (1ema)
Green fluorescent protein (1ema)

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.

Exploring the Structure

Insert caption here

Drag the structure with the mouse to rotate

GFP is a beta barrel protein with 11 beta sheets. It is a 26.9kDa protein made up of 238 amino acids. The , 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.[1]

  1. ↑ Ormo M, Cubitt AB, Kallio K, Gross LA, Tsien RY, Remington SJ. Crystal structure of the Aequorea victoria green fluorescent protein. Science. 1996 Sep 6;273(5280):1392-5. PMID:8703075

Quiz

1. How many alpha helices are in this structure?

One
None
Eleven
Twelve

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