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HOME > Product category > Fluorescent proteins > Umikinoko-Green


  • Bright green fluorescence
  • FRET donor with high pH stability

The fluorescent protein Umikinoko-Green (UkG) gene was isolated from the soft coral Sarcophyton sp. (umi-kinoko in Japanese).
UkG rapidly matures to form a dimeric complex. CoralHue™ monomeric Umikinoko-Green (mUkG1) maintains the brightness and pH stability of parent protein UkG. mUkG1 absorbs light maximally at 483 nm and emits green light at 499 nm. mUkG1 exhibits brilliant fluorescence and has extremely high pH stability. mUkG1 can be used to label proteins, subcellular structures or for FRET analysis.


Fluorescent properties

Umikinoko-Green spectrum data files (text files)
Umikinoko-Green excitation (4K)  Umikinoko-Green emission (8K)

Note: The file is in a tab-delimited text format. It contains values of the wavelength (0.5nm spacing) and brightness (fluorescence intensity peak value normalized to 1). Use a spreadsheet program to create a spectrum that will help you in choosing the appropriate excitation filter, dichroic mirror and fluorescence filter.

Oligomerization monomer
Number of amino acid 227
Excit./Emiss. maxima (nm) 483/499
Molar extinction coefficient (M-1cm-1) 60,000 (483 nm)
Fluorescence quantum yield 0.72
Brightness*1 43.2
pH sensitivity pKa=5.2
Cytotoxicity*2 No

*1Brightness: Molar Extinction Coefficient ×Fluorescence Quantum Yield / 1000
*2Toxicity when expressed in HeLa cells


Performance and use

Voltage sensor “Mermaid”

AG resistant to acidityMermaid is a membrane potential reporter using FRET. The structure of Mermaid consisting of the VSD of Ci-VSP and mUkG1-mKOκ in tandem. mUKG1 and mKO-κ are good FRET partners of donor and acceptor. mUKG's emission and mKO-κ's absorption greatly overlapped with a calculated Förster distance of 5.5 nm.


  • Tsutsui H, Karasawa S, Okamura Y, Miyawaki A. Improving membrane voltage measurements using FRET with new fluorescent proteins.; Nat Methods., 5, 683-685(2008) PMID:18622396

CoralHue™ fluorescent proteins were co-developed with the Laboratory for Cell Function and Dynamics, the Advanced Technology Development Center, the Brain Science Institute, RIKEN. MBL possesses the license and deals in the products.

Please send us a completed and signed License Acknowledgement.

Please note that the product will be shipped after we receive a completed and signed License Acknowledgement (PDF file on the right). Prior to shipping, our staff may contact you to verify the intended use of the product. Please also note that a separate agreement or a contract may be required depending on the intended use.
The product you have ordered is sold for research purpose only. It is not intended for industrial or clinical use, and shall not be used for any purposes other than research. You are also asked not to hand over or resell the product to a third party.
If you belong to a profit organization or a business corporation, or wish to use the product for profit or commercial purposes, please contact us.