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== Structure ==
== Structure ==
<applet load='1j6z' size='175' color='white' frame='true' align='right' caption='Globular Actin (G-actin): PDB identifier [http://www.rcsb.org/pdb/explore/explore.do?structureId=1J6Z/ 1J6Z].'/>
<applet load='1j6z' size='175' color='white' frame='true' align='right' caption='Globular Actin (G-actin): PDB identifier [http://www.rcsb.org/pdb/explore/explore.do?structureId=1J6Z/ 1J6Z].'/>
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<applet load='2zwh' size='175' color='white' frame='true' align='left' caption='Filamentous Actin (F-actin)'/>
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=== History of the structure ===
=== History of the structure ===
The F-actin protein was discovered by Straub in 1942. The structure was speculated based on a low-resolution x-ray crystallograph found in 1990 by Holmes et al. and over this time, despite the importance of F-actin in eukaryotic cells, this speculated structure was accepted. A higher resolution structure was only recently deposited in the PDB databank in Decemeber 2008 by Oda et al. <ref> Oda T, Iwasa M, Aihara T, Maéda Y, and Narita A. 2009. The nature of the globular-to fibrous actin transition. Nature,457(7228):441-445. PMID: [http://www.ncbi.nlm.nih.gov/pubmed/19158791/ 19158791]</ref>.
The F-actin protein was discovered by Straub in 1942. The structure was speculated based on a low-resolution x-ray crystallograph found in 1990 by Holmes et al. and over this time, despite the importance of F-actin in eukaryotic cells, this speculated structure was accepted. A higher resolution structure was only recently deposited in the PDB databank in Decemeber 2008 by Oda et al. <ref> Oda T, Iwasa M, Aihara T, Maéda Y, and Narita A. 2009. The nature of the globular-to fibrous actin transition. Nature,457(7228):441-445. PMID: [http://www.ncbi.nlm.nih.gov/pubmed/19158791/ 19158791]</ref>.
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=== Polymer F-actin ===
=== Polymer F-actin ===
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<applet load='2zwh' size='175' color='white' frame='true' align='left' caption='Filamentous Actin (F-actin)'/>
<scene name='Sandbox_154/Thing_in_the_middle/1'>This thing in the middle</scene>
<scene name='Sandbox_154/Thing_in_the_middle/1'>This thing in the middle</scene>
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Structurally, F-actin appears like a double right-handed helix. It is actually composed of 13 actin units for every 6 left-handed turns, which each have 166° rotations, occurring over 350 Å . <ref> Holmes, K.C., Popp, D., Gebhard, W. and Kabsch, W. 1990. Atomic model of the actin filament. Nature,347(6288):44-49. PMID: [http://www.ncbi.nlm.nih.gov/pubmed/2395461/ 2395461]</ref>.
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F-actin has the appearance of two right-handed helices. It is actually composed of repeats of 13 actin units for every 6 left-handed turns, spanning a length of 350 Å. <ref> Holmes, K.C., Popp, D., Gebhard, W. and Kabsch, W. 1990. Atomic model of the actin filament. Nature,347(6288):44-49. PMID: [http://www.ncbi.nlm.nih.gov/pubmed/2395461/ 2395461]</ref>. Including the ADP and Ca<sup>2+</sup>, the F-actin molecule as shown here consists of 377 residues (43kDa), two major domains and a nucleotide-binding cleft<ref>oda</ref>. Depending on the state of the bound nucleotide, the conformation of F-actin changes. It is most closed in its ADP+Pi bound state, and most open after the loss of gamma phosphate.
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Revision as of 04:22, 26 March 2010

PDB ID 2zwh

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2zwh, resolution 3.30Å ()
Ligands: ,
Non-Standard Residues:


Resources: FirstGlance, OCA, RCSB, PDBsum
Coordinates: save as pdb, mmCIF, xml


Contents

F-Actin

Filamentous actin (F-actin) is also referred to as microfilament [1] and is a highly conserved proteinous component found near ubiquitously in eukaryotic cytoskeletons. F-actin and other actin proteins generally provide a structural role to the cell.

Introduction

Actin is found in nearly all eukaryotic cells and is known primarily for its function as a structural and translocation protein. It also has an ATPase function, as it hydrolyzes ATP --> ADP + Pi and undergoes conformational changes with each hydrolysis. Actin belongs to the actin superfamily, which includes other proteins such as Hsp70 and hexokinase, because of its nucelotide-dependent conformational change reference Graceffa. Prokaryotes are not known to have actin, but do however have an actin homologue, MreB reference

Actin occurs in two forms: globular actin (G-actin), the free monomeric units of actin, and filamentous actin (F-actin) which is the polymer form. These two forms exist in a dynamic equilibrium with one another as ATP-associated polymerization and depolymerization occur continuously within the cell.

Assembly

Structure

Globular Actin (G-actin): PDB identifier 1J6Z.

Drag the structure with the mouse to rotate

History of the structure

The F-actin protein was discovered by Straub in 1942. The structure was speculated based on a low-resolution x-ray crystallograph found in 1990 by Holmes et al. and over this time, despite the importance of F-actin in eukaryotic cells, this speculated structure was accepted. A higher resolution structure was only recently deposited in the PDB databank in Decemeber 2008 by Oda et al. [2].

Monomeric Unit - G-actin

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Polymer F-actin

Filamentous Actin (F-actin)

Drag the structure with the mouse to rotate

F-actin has the appearance of two right-handed helices. It is actually composed of repeats of 13 actin units for every 6 left-handed turns, spanning a length of 350 Å. [3]. Including the ADP and Ca2+, the F-actin molecule as shown here consists of 377 residues (43kDa), two major domains and a nucleotide-binding cleft[4]. Depending on the state of the bound nucleotide, the conformation of F-actin changes. It is most closed in its ADP+Pi bound state, and most open after the loss of gamma phosphate. aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa






Domains

Function

Enzymatic Role

Active Site

Ligand

Structural Role

References

  1. ↑ Microfilament - Wikipedia, the free encyclopedia. http://en.wikipedia.org/wiki/Microfilaments. Date accessed: March 16th, 2010.
  2. ↑ Oda T, Iwasa M, Aihara T, Maéda Y, and Narita A. 2009. The nature of the globular-to fibrous actin transition. Nature,457(7228):441-445. PMID: 19158791
  3. ↑ Holmes, K.C., Popp, D., Gebhard, W. and Kabsch, W. 1990. Atomic model of the actin filament. Nature,347(6288):44-49. PMID: 2395461
  4. ↑ oda







Please do NOT make changes to this Sandbox until after April 23, 2010. Sandboxes 151-200 are reserved until then for use by the Chemistry 307 class at UNBC taught by Prof. Andrea Gorrell.
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