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spinqualitylabelsall models PDB ID 2zwh Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
2zwh, resolution 3.30Å ()
Ligands:	,
Non-Standard Residues:
Structural annotation: Resources: InterPro : Ipr004000, Ipr020902, Ipr004001 Pfam : PF00022 UniProt : P68135
Resources:	FirstGlance, OCA, RCSB, PDBsum
Coordinates:	save as pdb, mmCIF, xml

Contents 1 F-Actin 1.1 Introduction 1.2 Assembly 1.3 Structure 1.3.1 History of the structure 1.3.2 Monomeric Unit - G-actin 1.3.3 Polymer F-actin 1.3.4 Domains 1.4 Function 1.4.1 Enzymatic Role 1.4.1.1 Active Site 1.4.1.2 Ligand 1.4.2 Structural Role 1.5 References

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 as part of its assembly process.

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

Assembly

Structure

spinqualitylabelsall models Globular Actin (G-actin): PDB identifier 1J6Z. Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

spinqualitylabelsall models Filamentous Actin (F-actin) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

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, this speculated structure was accepted. The 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

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 . ^[3]. 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

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