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Fluorescent Sensor
Overview of Fluorescent Sensor
Biological sensors are fundamental to current research, from quantifying metabolites under different perturbations to identifying cell states. Many types of sensors exist with a variety of readouts, with one of the most widely used platforms being fluorescent sensors. Fluorescent sensor molecules for imaging cellular molecules have become a hot topic in chemical biology research during the last two decades. A fluorescent sensor is advantageous due to its high sensitivity.
Fig.1 Metabolic targets of fluorescent biosensors in neurons. (Koveal, 2020)
Application of Fluorescent Sensor in Neuroscience
In neuroscience, the most applied fluorescent sensors are genetically encoded calcium indicators (GECIs), genetically encoded voltage indicators (GEVIs), and pH sensors (pHluorins). Numerous other fluorescent indicators have been applied to study brain cell activity, including sensors for inorganic ions and molecules (chloride, zinc, hydrogen peroxide) and organic signaling molecules and metabolites (glutamate, acetylcholine, ATP, NADH, cyclic nucleotides, glucose, pyruvate, phospholipids). Several sensors that directly monitor enzyme activity have also been developed. These allow the activity of small GTPases, kinases (e.g., protein kinase A), and proteases to be detected. Moreover, GPCR activation can be followed by intra- or intermolecular FRET, either within the heterodimeric G protein or between the GPCR and a binding partner (G protein or arrestin). This approach has been applied to analyze the activation kinetics of metabotropic glutamate receptors, GABAB receptors, and M1 muscarinic acetylcholine receptors.
| Sensor | Scaffold | Fluorescent Protein(s) | Excitation | Emission | Sensor Design | Dynamic range: fold change or Δ lifetime | Affinity (Kd or KR) |
|---|---|---|---|---|---|---|---|
| ATP | |||||||
| ATeam1.03 | F0F1-ATP synthase, ε subunit (B. subtilis) | mseCFP/ mVenus | 435 nm (D) |
475 nm (D) 527 nm (A) |
FRET | 2.3-fold (37℃) | 3.3 mM |
| ATeam1.03YEMK | F0F1-ATP synthase, ε subunit (B. subtilis) | mseCFP/ mVenus | 435 nm (D) |
475 nm (D) 527 nm (A) |
FRET | n.r. |
1.2 mM (37℃) 2.6 mM (20-22℃) |
| QUEEN-2m | F0F1-ATP synthase, ε subunit (B. subtilis) | cp-EGFP | 400 nm / 494 nm | 513 nm | Ratiometric (excitation) | >3-fold (25℃) | 2.4 mM |
| QUEEN-7μ | F0F1-ATP synthase, ε subunit (B. PS3) | cp-EGFP | 400 nm / 494 nm | 513 nm | Ratiometric (excitation) |
~4.3-fold (37℃) ~5-fold (25℃) |
14 μM 7.2 μM |
| iATPSnFR1.0 | F0F1-ATP synthase, ε subunit (B. PS3) | cp-SFGFP | 488 nm | 515 nm | Intensity | 2-fold (RT) | 350 μM |
| iATPSnFR1.1 | F0F1-ATP synthase, ε subunit (B. PS3) | cp-SFGFP | 488 nm | 515 nm | Intensity | 1.88-fold (RT) | 138 μM |
| ATP:ADP | |||||||
| PercevalHR | GlnK, nucleotide binding protein (M. jannaschii) | cp-mVenus | 482 nm / 455 nm | 529 nm | Ratiometric (excitation) |
4.6-fold (37℃) ~4-fold (RT) |
ATP:ADP ≈ 6.1 ATP:ADP ≈ 3.5 |
| NADH | |||||||
| Frex | B-Rex, NADH binding protein (B. subtilis) | cpYFP | 488 nm / 405 nm | 525 nm | Ratiometric (excitation) | ~9.5-fold (RT) | 3.7 μM |
| NADH:NAD+ | |||||||
| SoNar | T-Rex, NADH binding protein (T. aquaticus) | cpYFP | 420 nm / 485 nm | 528 nm | Ratiometric (excitation) | ~15-fold (RT) | NADH:NAD+ ≈ 1/40 |
| Peredox | T-Rex, NADH binding protein (T. aquaticus) | cp-T- Sapphire | 400 nm | 510 nm | Intensityb | 2.5-fold (35℃) | NADH:NAD+ ≈ 1/90 |
| 800 nm (two-photon) | 525 nm | Lifetime |
0.9 ns (35℃) 0.8 ns (25℃) |
NADH:NAD+ ≈ 1/255 NADH:NAD+ ≈ 1/529 | |||
| Glucose | |||||||
| FLII12Pglu700μ∆6 | MglB, glucose/galactose binding protein (E. coli) | eCFP/ Citrine | 433 nm (D) |
485 nm (D) 528 nm (A) |
FRET | 1.5-fold (RT) | 660 μM |
| Green Glifon600 | MglB, glucose/galactose binding protein (E. coli) | Citrine | 480 nm | 530 nm | Intensity | ~5-fold (RT) | 590 μM |
| Green Glifon4000 | MglB, glucose/galactose binding protein (E. coli) | Citrine | 480 nm | 530 nm | Intensity | ~6-fold (RT) | 3.8 mM |
| iGlucoSnFR | GGBP, glucose/ galactose binding protein (T. thermophilus) | cpGFP | 485 nm | 515 nm | Intensity | 3.32-fold (RT) | 7.7 mM |
| iGlucoSnFR-TS | GGBP, glucose/ galactose binding protein (T. thermophilus) | cp-T- Sapphire | 790 nm (two-photon) | 525 nm | Lifetime |
0.34 ns (37℃) 0.38 ns (37℃) |
2.2 mM 1.8 mMc |
| Lactate | |||||||
| Laconic | LldR, lactate binding transcription regulator (E. coli) | mTFP/ Venus | 430 nm (D) |
480 nm (D) 535 nm (A) |
FRET | ~1.2-fold (25℃) |
Biphasic: K1 = 8 µM K2 = 830 µM |
| Pyruvate | |||||||
| Pyronic | PdhR, pyruvate dehydrogenase complex repressor (E. coli) | mTFP/ Venus | 430 nm (D) |
480 nm (D) 535 nm (A) |
FRET | ~1.24-fold (RT) | 107 μM |
Table1 Genetically encoded fluorescent biosensors used for the study of neuronal metabolism
Services at Creative Biolabs
With professional expertise, advanced technology platforms, excellent specialists, and rich experience in neuroscience, Creative Biolabs has gained a good reputation in the industry. Years of practice devoted to neuroscience research make us experienced in fluorescent sensors' application in this field. With all these advantages, we are confident in providing customers high-quality relevantly custom productions. If you are interested in applying fluorescent sensors in neuroscience research or have any other inquiries on neuro-based custom productions, please feel free to contact us for more information.
Reference
- Koveal, D.; et al. Fluorescent Biosensors for Neuronal Metabolism and the Challenges of Quantitation. Curr Opin Neurobiol. 2020, 63: 111-121.
For Research Use Only. Not For Clinical Use.