Biological Assembly 1  

 3D View: Structure | Electron Density

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 27.32 kDa 
• Atom Count: 1949 
• Residue Count: 231 
• Unique protein chains: 1

1HUY

CRYSTAL STRUCTURE OF CITRINE, AN IMPROVED YELLOW VARIANT OF GREEN FLUORESCENT PROTEIN

• DOI: 10.2210/pdb1HUY/pdb

• Classification: LUMINESCENT PROTEIN
• Organism(s): Aequorea victoria
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2001-01-04 Released: 2001-07-04 
• Deposition Author(s): Griesbeck, O., Baird, G.S., Campbell, R.E., Zacharias, D.A., Tsien, R.Y.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.20 Å
• R-Value Free: 0.208 
• R-Value Work: 0.164 
• R-Value Observed: 0.164 

Literature

Reducing the environmental sensitivity of yellow fluorescent protein. Mechanism and applications

Griesbeck, O., Baird, G.S., Campbell, R.E., Zacharias, D.A., Tsien, R.Y.

(2001) J Biol Chem 276: 29188-29194

• PubMed: 11387331 
• DOI: 10.1074/jbc.M102815200
• Primary Citation of Related Structures:  
  1HUY


• PubMed Abstract: 
  

Yellow mutants of the green fluorescent protein (YFP) are crucial constituents of genetically encoded indicators of signal transduction and fusions to monitor protein-protein interactions. However, previous YFPs show excessive pH sensitivity, chloride interference, poor photostability, or poor expression at 37 degrees C. Protein evolution in Escherichia coli has produced a new YFP named Citrine, in which the mutation Q69M confers a much lower pK(a) (5.7) than for previous YFPs, indifference to chloride, twice the photostability of previous YFPs, and much better expression at 37 degrees C and in organelles. The halide resistance is explained by a 2.2-A x-ray crystal structure of Citrine, showing that the methionine side chain fills what was once a large halide-binding cavity adjacent to the chromophore. Insertion of calmodulin within Citrine or fusion of cyan fluorescent protein, calmodulin, a calmodulin-binding peptide and Citrine has generated improved calcium indicators. These chimeras can be targeted to multiple cellular locations and have permitted the first single-cell imaging of free [Ca(2+)] in the Golgi. Citrine is superior to all previous YFPs except when pH or halide sensitivity is desired and is particularly advantageous within genetically encoded fluorescent indicators of physiological signals.

---

Organizational Affiliation: 

Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093-0647, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
GREEN FLUORESCENT PROTEIN	A	239	Aequorea victoria	Mutation(s): 5  Gene Names: GFP
Find proteins for P42212 (Aequorea victoria) Explore P42212  Go to UniProtKB:  P42212

Small Molecules

Modified Residues  1 Unique
ID	Chains	Type	Formula	2D Diagram	Parent
CRO	A	L-PEPTIDE LINKING	C15 H17 N3 O5		THR, TYR, GLY

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.20 Å
• R-Value Free: 0.208 
• R-Value Work: 0.164 
• R-Value Observed: 0.164 
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 52.504	α = 90
b = 61.758	β = 90
c = 70.684	γ = 90

Software Package:

Software Name	Purpose
MAR345	data collection
SCALEPACK	data scaling
CNS	refinement
CNS	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2001-01-04 
• Released Date: 2001-07-04 
Deposition Author(s): Griesbeck, O., Baird, G.S., Campbell, R.E., Zacharias, D.A., Tsien, R.Y.

Revision History 

• Version 1.0: 2001-07-04
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2017-10-04
  Changes: Refinement description