GFP Expression Marker System

About the GFP Expression Marker System

GFP Expression Marker System used green fluorescent protein, or GFP, as a visible marker in living cells. It enabled users to link GFP to a regulatory DNA element or to a protein of interest, then detect fluorescence under near-UV or blue light to monitor gene expression, select expressing cells, or localize proteins without exogenously added substrates or cofactors.
Core Technology
TBD
Technical Aspect/ParametersGFP Expression Marker SystemConventional Approach
Signal sourceUsed Aequorea victoria green fluorescent protein as the visible marker.Used reporter systems such as β-galactosidase, firefly luciferase, or bacterial luciferase.
Need for added compoundsPatent stated detection required near-UV or blue light and no exogenously added compounds.Patent stated these methods could require added substrates or cofactors.
Gene expression readoutA regulatory element was operatively linked to GFP so fluorescence indicated expression.Not specified.
Localization methodA protein of interest was fused to GFP so fluorescence showed location in the cell.Older marker methods described in the patent often required added substrates, cofactors, or fixed preparations.
Cell selection methodIn the claimed method, cells expressing GFP were selected to select cells expressing the paired protein of interest.Not specified.
Host range describedThe patent described bacterial, yeast, fungal, insect, nematode, plant, and animal cells.Not specified.
Stimulus and detection usePromoter-controlled GFP indicated heavy metals, stress responses, pollutants, or certain target molecules described in the patent.Not specified.
Technical SpecificationReported in Patent
Source proteinAequorea victoria green fluorescent protein (GFP)
Protein length238 amino acids
Main excitation peak395 nm
Minor excitation peak470 nm
Peak emission509 nm
Emission shoulder540 nm
Detection modeFluorescence under near-UV or blue light
Substrates/cofactorsNot required
Gene productsNot required
ConstructpGFP10.1
Coding changeCodon 80, CAG→CGG
Amino acid changeGln→Arg
Reported effect of mutationNo detectable change in spectral properties
Model organismsE. coli and C. elegans
ATCC depositpGFP10.1, Accession 75547
  • Monitored gene expression in living cells by linking a regulatory element to GFP.
  • Localized a protein of interest in a cell by expressing a GFP fusion protein.
  • Selected cells that expressed a protein of interest by selecting cells that fluoresced.
  • Separated fluorescent cells with fluorescence-activated cell sorting.
  • Tracked the effects of external stimuli on a regulatory element through changes in fluorescence.
  • Determined tissue-specific activity of a DNA sequence in a subject.
  • Indicated gene expression in cells or subjects through visible fluorescence.
  • Detected heavy metals in a solution using a promoter activated by heavy metal exposure.
  • Detected pollutants in a solution using heavy-metal-responsive or stress-protein promoters.
  • Detected target bacteria or cell types using bacteriophages or viruses that carried the GFP gene.

Validation to date included the original patent demonstrations in E. coli and C. elegans, and the technology later developed into a widely used research tool for live-cell imaging, gene expression reporting, and protein localization. After the original patent period, GFP and related fluorescent proteins were further engineered into broader imaging toolsets and were recognized in 2008 by the Nobel Prize in Chemistry for the discovery and development of GFP.

About the GFP Expression Marker System

Overview

GFP Expression Marker System used green fluorescent protein, or GFP, as a visible marker in living cells. It enabled users to link GFP to a regulatory DNA element or to a protein of interest, then detect fluorescence under near-UV or blue light to monitor gene expression, select expressing cells, or localize proteins without exogenously added substrates or cofactors.
Intellectual Property

 

GFP Expression Marker System placed DNA that encoded Aequorea victoria green fluorescent protein under the control of a selected regulatory element, or linked GFP to DNA that encoded a protein of interest. When the regulatory element directed expression, the cell produced GFP and became fluorescent under near-UV or blue light. When GFP was fused to a protein of interest, the fluorescence showed where that fused protein was located inside the cell. The patent also described a selection method that introduced DNA for the protein of interest together with DNA for GFP, then selected cells that fluoresced. The same approach indicated gene expression, showed tissue specificity, and reported promoter responses associated with heavy metals, stress-related pathways, or certain molecules described in the patent.

 

Earlier marker methods described in the patent, such as β-galactosidase and luciferase systems, were limited because they often required fixed samples or added substrates and cofactors. Those steps made work with living tissue harder and interrupted direct observation over time.

GFP addressed that gap by using fluorescence that the patent said could be detected after excitation with near-UV or blue light, without exogenously added substrates or cofactors. This supported direct observation of living cells and organisms while gene activity or protein location was being studied.

The invention also addressed a screening problem: identifying cells that expressed a protein of interest. In the claimed method, selecting GFP-expressing cells was used to select cells expressing the protein of interest. The patent further described use as a visible indicator for external stimuli, tissue-specific activity, and detection tasks tied to promoter response

Technical Aspect/ParametersGFP Expression Marker SystemConventional Approach
Signal sourceUsed Aequorea victoria green fluorescent protein as the visible marker.Used reporter systems such as β-galactosidase, firefly luciferase, or bacterial luciferase.
Need for added compoundsPatent stated detection required near-UV or blue light and no exogenously added compounds.Patent stated these methods could require added substrates or cofactors.
Gene expression readoutA regulatory element was operatively linked to GFP so fluorescence indicated expression.Not specified.
Localization methodA protein of interest was fused to GFP so fluorescence showed location in the cell.Older marker methods described in the patent often required added substrates, cofactors, or fixed preparations.
Cell selection methodIn the claimed method, cells expressing GFP were selected to select cells expressing the paired protein of interest.Not specified.
Host range describedThe patent described bacterial, yeast, fungal, insect, nematode, plant, and animal cells.Not specified.
Stimulus and detection usePromoter-controlled GFP indicated heavy metals, stress responses, pollutants, or certain target molecules described in the patent.Not specified.
Technical SpecificationReported in Patent
Source proteinAequorea victoria green fluorescent protein (GFP)
Protein length238 amino acids
Main excitation peak395 nm
Minor excitation peak470 nm
Peak emission509 nm
Emission shoulder540 nm
Detection modeFluorescence under near-UV or blue light
Substrates/cofactorsNot required
Gene productsNot required
ConstructpGFP10.1
Coding changeCodon 80, CAG→CGG
Amino acid changeGln→Arg
Reported effect of mutationNo detectable change in spectral properties
Model organismsE. coli and C. elegans
ATCC depositpGFP10.1, Accession 75547
  • Monitored gene expression in living cells by linking a regulatory element to GFP.
  • Localized a protein of interest in a cell by expressing a GFP fusion protein.
  • Selected cells that expressed a protein of interest by selecting cells that fluoresced.
  • Separated fluorescent cells with fluorescence-activated cell sorting.
  • Tracked the effects of external stimuli on a regulatory element through changes in fluorescence.
  • Determined tissue-specific activity of a DNA sequence in a subject.
  • Indicated gene expression in cells or subjects through visible fluorescence.
  • Detected heavy metals in a solution using a promoter activated by heavy metal exposure.
  • Detected pollutants in a solution using heavy-metal-responsive or stress-protein promoters.
  • Detected target bacteria or cell types using bacteriophages or viruses that carried the GFP gene.

Validation to date included the original patent demonstrations in E. coli and C. elegans, and the technology later developed into a widely used research tool for live-cell imaging, gene expression reporting, and protein localization. After the original patent period, GFP and related fluorescent proteins were further engineered into broader imaging toolsets and were recognized in 2008 by the Nobel Prize in Chemistry for the discovery and development of GFP.

Case Number

WHOI-OW-481

Patent

US5491084A

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