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Dextran, Biotin, 10,000 MW, Lysine Fixable (BDA-10,000) (Invitrogen™)

Labeled dextrans are hydrophilic polysaccharides most commonly used in microscopy studies to monitor cell division, track the movement of live cells, and to report the hydrodynamic properties of the cytoplasmic matrix. The labeled dextran is commonly introduced into the cells via microinjection.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Dextran Specifications:

Label (Ex/Em): None (Biotinylated)
Size: 10,000 MW
Charge: Anionic
Fixable: Fixable via Lysine

High Manufacturing Standards of Molecular Probes® Dextrans
We offer more than 50 fluorescent and biotinylated dextran conjugates in several molecular weight ranges. Dextrans are hydrophilic polysaccharides characterized by their moderate-to-high molecular weight, good water solubility, and low toxicity. They also generally exhibit low immunogeniticy. Dextrans are biologically inert due to their uncommon poly-(α-D-1,6-glucose) linkages, which render them resistant to cleavage by most endogenous cellular glycosidases.

In most cases, Molecular Probes® fluorescent dextrans are much brighter and have higher negative charge than dextrans available from other sources. Furthermore, we use rigorous methods for removing as much unconjugated dye as practical, and then assay our dextran conjugates by thin-layer chromatography to help ensure the absence of low molecular weight contaminants.

A Wide Selection of Substituents and Molecular Weights
Molecular Probes® dextrans are conjugated to biotin or a wide variety of fluorophores, including seven of our Alexa Fluor® dyes (Molecular Probes dextran conjugates–Table 14.4) and are available in these nominal molecular weights (MW): 3,000; 10,000; 40,000; 70,000; 500,000; and 2,000,000 daltons.

Dextran Net Charge and Fixability
We employ succinimidyl coupling of our dyes to the dextran molecule, which, in most cases, results in a neutral or anionic dextran. The reaction used to produce the Rhodamine Green™ and Alexa Fluor® 488 dextrans results in the final product being neutral, anionic, or cationic. The Alexa Fluor®, Cascade Blue®, lucifer yellow, fluorescein, and Oregon Green® dextrans are intrinsically anionic, whereas most of the dextrans labeled with the zwitterionic rhodamine B, tetramethylrhodamine, and Texas Red® dyes are essentially neutral. To produce more highly anionic dextrans, we have developed a proprietary procedure for adding negatively charged groups to the dextran carriers; these products are designated "polyanionic" dextrans.

Some applications require that the dextran tracer be treated with formaldehyde or glutaraldehyde for subsequent analysis. For these applications, we offer "lysine-fixable" versions of most of our dextran conjugates of fluorophores or biotin. These dextrans have covalently bound lysine residues that permit dextran tracers to be conjugated to surrounding biomolecules by aldehyde-mediated fixation for subsequent detection by immunohistochemical and ultrastructural techniques. We have also shown that all of our 10,000 MW Alexa Fluor® dextran conjugates can be fixed with aldehyde-based fixatives.

Key Applications Using Labeled Dextrans
There are a multitude of citations describing the use of labeled dextrans. Some of the most common uses include:

Neuronal tracing (anterograde and retrograde) in live cells
Cell lineage tracing in live cells
Neuroanatomical tracing
Examining intercellular communications (e.g., in gap junctions, during wound healing, and during embryonic development)
Investigating vascular permeability and blood–brain barrier integrity
Tracking endocytosis
Monitoring acidification (some dextran–dye conjugates are pH-sensitive)
Studying the hydrodynamic properties of the cytoplasmic matrix

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Epidermal Growth Factor, Biotinylated, complexed to Texas Red™ Streptavidin (Texas Red™ EGF complex) (Invitrogen™)

We offer several conjugates of epidermal growth factor that are useful for the detection of EGF receptor in cells. Fluorescently labeled EGF has enabled scientists to investigate receptor-membrane interactions, study receptor distribution, calculate rate constants for the interaction of EGF with its receptor, and more. The conjugates incorporating fluorescein (FITC), Oregon Green® 514, and tetramethylrhodamine were constructed with the dye directly attached to EGF. The conjugates of EGF with Alexa Fluor® dyes and Texas Red® dye are complexes of the dye–streptavidin molecule and biotinylated EGF. The biotinylated conjugates utilize biotin-XX, which contains a long spacer arm designed to enhance the probe’s affinity for the EGF receptor.

Epidermal Growth Factor Conjugate Specifications:
• EGF molecule: 53 amino acids, MW=6,045 Da
• Label (Ex/Em): Biotin-XX complexed with Texas Red® streptavidin (~595/615 nm)
• Number of fluorophore molecules on each EGF molecule: ~2–3
• Fluorescence is typically monitored using a flow cytometer, fluorescence microscope, or fluorimeter


Find More Receptor Binding and Phagocytosis Probes
We offer a number of fluorescently labeled probes for studying receptor-mediated endocytosis, membrane markers for endocytosis and exocytosis, and methods for detecting internalized fluorescent ligands. Review Probes for Following Receptor Binding and Phagocytosis—Section 16.1 in the Molecular Probes® Handbook for more information on these products.

For Research Use. Not for human or animal therapeutic or diagnostic use.

pHrodo™ Green Dextran, 10,000 MW, for Endocytosis (Invitrogen™)

New pH-sensitive pHrodo® Green dye conjugates, like our pHrodo® Red dye conjugates, give faster and more accurate results than any other phagocytosis assay. pHrodo® Green conjugates are non-fluorescent outside the cell at neutral pH, but fluoresce brightly green at acidic pH such as in phagosomes. Get faster staining and more accurate results—without the need for wash steps or quencher dye.

• Specific detection of phagocytosis and endocytosis
• Reduced signal variability and improved timing in sensitive experiments
• Enough for approx. 50 coverslips or two 96-well plates
• Multiplex with other compatible dyes, such as red florescent protein, TMRM, NucBlue™ Hoechst, and CellROX® Deep Red

The fluorescence of the novel pHrodo® Green dye dramatically increases as pH decreases from neutral to acidic, making it an ideal tool to study phagocytosis and its regulation by drugs and/or environmental factors. The lack of fluorescence outside the cell eliminates the need for wash steps and quencher dyes.

Use the ready-made pHrodo® Green Dextran 10,000 conjugate in imaging, high content screening, high throughput screening, and flow applications. pHrodo® Green dye is also available as a conjugate of E. coli BioParticles®, zymosan BioParticles®, or S. aureus BioParticles®. To create other conjugates, such as antibody conjugates, use pHrodo® Green STP ester or pHrodo® Green maleimide.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.

Dextran, Biotin, 70,000 MW, Lysine Fixable (BDA-70,000) (Invitrogen™)

Labeled dextrans are hydrophilic polysaccharides most commonly used in microscopy studies to monitor cell division, track the movement of live cells, and to report the hydrodynamic properties of the cytoplasmic matrix. The labeled dextran is commonly introduced into the cells via microinjection.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Dextran Specifications:

Label (Ex/Em): None (Biotinylated)
Size: 70,000 MW
Charge: Anionic
Fixable: Fixable via Lysine

High Manufacturing Standards of Molecular Probes® Dextrans
We offer more than 50 fluorescent and biotinylated dextran conjugates in several molecular weight ranges. Dextrans are hydrophilic polysaccharides characterized by their moderate-to-high molecular weight, good water solubility, and low toxicity. They also generally exhibit low immunogeniticy. Dextrans are biologically inert due to their uncommon poly-(α-D-1,6-glucose) linkages, which render them resistant to cleavage by most endogenous cellular glycosidases.

In most cases, Molecular Probes® fluorescent dextrans are much brighter and have higher negative charge than dextrans available from other sources. Furthermore, we use rigorous methods for removing as much unconjugated dye as practical, and then assay our dextran conjugates by thin-layer chromatography to help ensure the absence of low molecular weight contaminants.

A Wide Selection of Substituents and Molecular Weights
Molecular Probes® dextrans are conjugated to biotin or a wide variety of fluorophores, including seven of our Alexa Fluor® dyes (Molecular Probes dextran conjugates–Table 14.4) and are available in these nominal molecular weights (MW): 3,000; 10,000; 40,000; 70,000; 500,000; and 2,000,000 daltons.

Dextran Net Charge and Fixability
We employ succinimidyl coupling of our dyes to the dextran molecule, which, in most cases, results in a neutral or anionic dextran. The reaction used to produce the Rhodamine Green™ and Alexa Fluor® 488 dextrans results in the final product being neutral, anionic, or cationic. The Alexa Fluor®, Cascade Blue®, lucifer yellow, fluorescein, and Oregon Green® dextrans are intrinsically anionic, whereas most of the dextrans labeled with the zwitterionic rhodamine B, tetramethylrhodamine, and Texas Red® dyes are essentially neutral. To produce more highly anionic dextrans, we have developed a proprietary procedure for adding negatively charged groups to the dextran carriers; these products are designated "polyanionic" dextrans.

Some applications require that the dextran tracer be treated with formaldehyde or glutaraldehyde for subsequent analysis. For these applications, we offer "lysine-fixable" versions of most of our dextran conjugates of fluorophores or biotin. These dextrans have covalently bound lysine residues that permit dextran tracers to be conjugated to surrounding biomolecules by aldehyde-mediated fixation for subsequent detection by immunohistochemical and ultrastructural techniques. We have also shown that all of our 10,000 MW Alexa Fluor® dextran conjugates can be fixed with aldehyde-based fixatives.

Key Applications Using Labeled Dextrans
There are a multitude of citations describing the use of labeled dextrans. Some of the most common uses include:

Neuronal tracing (anterograde and retrograde) in live cells
Cell lineage tracing in live cells
Neuroanatomical tracing
Examining intercellular communications (e.g., in gap junctions, during wound healing, and during embryonic development)
Investigating vascular permeability and blood–brain barrier integrity
Tracking endocytosis
Monitoring acidification (some dextran–dye conjugates are pH-sensitive)
Studying the hydrodynamic properties of the cytoplasmic matrix

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Cholera Toxin Subunit B (Recombinant), Alexa Fluor™ 488 Conjugate (Invitrogen™)

Molecular Probes® cholera toxin conjugates are made from a recombinant version of the B subunit only. This allows us to provide a very high-purity product that is completely free of the toxic A subunit. Cholera toxin B subunit (CT-B) attaches to cells by binding to ganglioside GM1, making it a powerful tool for retrograde labeling of neurons. This tracer has been used in a variety of applications, including tracing of rat forebrain afferents, projections of the parabrachial region, and neurons of the urinary bladder wall. When used in neuronal tracing applications, CT-B is typically introduced by pressure injection or by iontophoretic injection into neural tissue.

Cholera Toxin Subunit B Specifications:
• Label (Ex/Em): Alexa Fluor® 488 (495/519 nm)
• At neutral pH, the 11.4 kDa B subunit exists as a 57 kDa pentamer
• Lyophilized product can be dissolved in buffer (e.g., PBS) for use


Cholera Toxin Subunit B for Studying Lipid Rafts
More recently, researchers have found that CT-B can be used as a marker for lipid rafts, which are membrane microdomains enriched in cholesterol and sphingolipids thought to be important in cell signaling. For lipid raft staining, cells are first incubated with fluorescent CT-B. Then, an anti–CT-B antibody is added to crosslink the CT-B in the lipid rafts into distinct patches on the plasma membrane. These patches are easily visualized by fluorescence microscopy. In addition to individual fluorescent CT-B conjugates, we also offer Vybrant® Lipid Raft Labeling Kits that contain the Alexa Fluor® 488, Alexa Fluor® 555, or Alexa Fluor® 594 dye conjugates of CT-B, an anti–CT-B antibody, and a detailed protocol for labeling and preparing cells for fluorescence microscopy.

Find More CT-B Conjugates
We offer various CT-B conjugates. Review Protein Conjugates—Section 14.7 in the Molecular Probes® Handbook for more information on these tracers.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.

Epidermal Growth Factor, Tetramethylrhodamine Conjugate (rhodamine EGF) (Invitrogen™)

We offer several conjugates of epidermal growth factor that are useful for the detection of EGF receptor in cells. Fluorescently labeled EGF has enabled scientists to investigate receptor-membrane interactions, study receptor distribution, calculate rate constants for the interaction of EGF with its receptor, and more. The conjugates incorporating fluorescein (FITC), Oregon Green® 514, and tetramethylrhodamine were constructed with the dye directly attached to EGF. The conjugates of EGF with Alexa Fluor® dyes and Texas Red® dye are complexes of the dye–streptavidin molecule and biotinylated EGF. The biotinylated conjugates utilize biotin-XX, which contains a long spacer arm designed to enhance the probe’s affinity for the EGF receptor.

Epidermal Growth Factor Conjugate Specifications:
• EGF molecule: 53 amino acids, MW=6,045 Da
• Label (Ex/Em): Tetramethylrhodamine (~555/580 nm)
• Number of fluorophore molecules on each EGF molecule: 1
• Fluorescence is typically monitored using a flow cytometer, fluorescence microscope, or fluorimeter


Find More Receptor Binding and Phagocytosis Probes
We offer a number of fluorescently labeled probes for studying receptor-mediated endocytosis, membrane markers for endocytosis and exocytosis, and methods for detecting internalized fluorescent ligands. Review Probes for Following Receptor Binding and Phagocytosis—Section 16.1 in the Molecular Probes® Handbook for more information on these products.

For Research Use. Not for human or animal therapeutic or diagnostic use.

Dextran, Cascade Blue™, 10,000 MW, Anionic, Lysine Fixable (Invitrogen™)

Labeled dextrans are hydrophilic polysaccharides most commonly used in microscopy studies to monitor cell division, track the movement of live cells, and to report the hydrodynamic properties of the cytoplasmic matrix. The labeled dextran is commonly introduced into the cells via microinjection.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Dextran Specifications:

Label (Ex/Em): Cascade Blue® (400/420)
Size: 10,000 MW
Charge: Anionic
Fixable: Fixable via Lysine

High Manufacturing Standards of Molecular Probes® Dextrans
We offer more than 50 fluorescent and biotinylated dextran conjugates in several molecular weight ranges. Dextrans are hydrophilic polysaccharides characterized by their moderate-to-high molecular weight, good water solubility, and low toxicity. They also generally exhibit low immunogeniticy. Dextrans are biologically inert due to their uncommon poly-(α-D-1,6-glucose) linkages, which render them resistant to cleavage by most endogenous cellular glycosidases.

In most cases, Molecular Probes® fluorescent dextrans are much brighter and have higher negative charge than dextrans available from other sources. Furthermore, we use rigorous methods for removing as much unconjugated dye as practical, and then assay our dextran conjugates by thin-layer chromatography to help ensure the absence of low molecular weight contaminants.

A Wide Selection of Substituents and Molecular Weights
Molecular Probes® dextrans are conjugated to biotin or a wide variety of fluorophores, including seven of our Alexa Fluor® dyes (Molecular Probes dextran conjugates–Table 14.4) and are available in these nominal molecular weights (MW): 3,000; 10,000; 40,000; 70,000; 500,000; and 2,000,000 daltons.

Dextran Net Charge and Fixability
We employ succinimidyl coupling of our dyes to the dextran molecule, which, in most cases, results in a neutral or anionic dextran. The reaction used to produce the Rhodamine Green™ and Alexa Fluor® 488 dextrans results in the final product being neutral, anionic, or cationic. The Alexa Fluor®, Cascade Blue®, lucifer yellow, fluorescein, and Oregon Green® dextrans are intrinsically anionic, whereas most of the dextrans labeled with the zwitterionic rhodamine B, tetramethylrhodamine, and Texas Red® dyes are essentially neutral. To produce more highly anionic dextrans, we have developed a proprietary procedure for adding negatively charged groups to the dextran carriers; these products are designated "polyanionic" dextrans.

Some applications require that the dextran tracer be treated with formaldehyde or glutaraldehyde for subsequent analysis. For these applications, we offer "lysine-fixable" versions of most of our dextran conjugates of fluorophores or biotin. These dextrans have covalently bound lysine residues that permit dextran tracers to be conjugated to surrounding biomolecules by aldehyde-mediated fixation for subsequent detection by immunohistochemical and ultrastructural techniques. We have also shown that all of our 10,000 MW Alexa Fluor® dextran conjugates can be fixed with aldehyde-based fixatives.

Key Applications Using Labeled Dextrans
There are a multitude of citations describing the use of labeled dextrans. Some of the most common uses include:

Neuronal tracing (anterograde and retrograde) in live cells
Cell lineage tracing in live cells
Neuroanatomical tracing
Examining intercellular communications (e.g., in gap junctions, during wound healing, and during embryonic development)
Investigating vascular permeability and blood–brain barrier integrity
Tracking endocytosis
Monitoring acidification (some dextran–dye conjugates are pH-sensitive)
Studying the hydrodynamic properties of the cytoplasmic matrix

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Cholera Toxin Subunit B (Recombinant), Alexa Fluor™ 555 Conjugate (Invitrogen™)

Molecular Probes® cholera toxin conjugates are made from a recombinant version of the B subunit only. This allows us to provide a very high-purity product that is completely free of the toxic A subunit. Cholera toxin B subunit (CT-B) attaches to cells by binding to ganglioside GM1, making it a powerful tool for retrograde labeling of neurons. This tracer has been used in a variety of applications, including tracing of rat forebrain afferents, projections of the parabrachial region, and neurons of the urinary bladder wall. When used in neuronal tracing applications, CT-B is typically introduced by pressure injection or by iontophoretic injection into neural tissue.

Cholera Toxin Subunit B Specifications:
• Label (Ex/Em): Alexa Fluor® 555 (555/565 nm)
• At neutral pH, the 11.4 kDa B subunit exists as a 57 kDa pentamer
• Lyophilized product can be dissolved in buffer (e.g., PBS) for use


Cholera Toxin Subunit B for Studying Lipid Rafts
More recently, researchers have found that CT-B can be used as a marker for lipid rafts, which are membrane microdomains enriched in cholesterol and sphingolipids thought to be important in cell signaling. For lipid raft staining, cells are first incubated with fluorescent CT-B. Then, an anti–CT-B antibody is added to crosslink the CT-B in the lipid rafts into distinct patches on the plasma membrane. These patches are easily visualized by fluorescence microscopy. In addition to individual fluorescent CT-B conjugates, we also offer Vybrant® Lipid Raft Labeling Kits that contain the Alexa Fluor® 488, Alexa Fluor® 555, or Alexa Fluor® 594 dye conjugates of CT-B, an anti–CT-B antibody, and a detailed protocol for labeling and preparing cells for fluorescence microscopy.

Find More CT-B Conjugates
We offer various CT-B conjugates. Review Protein Conjugates—Section 14.7 in the Molecular Probes® Handbook for more information on these tracers.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.

Albumin from Bovine Serum (BSA), Alexa Fluor™ 488 conjugate (Invitrogen™)

This albumin from bovine serum (BSA), Alexa Fluor 488 conjugate is a bright and photostable conjugate exceptionally suited for applications in which well-defined molecular weight tracers are needed. These applications include studying the rate of endocytosis and exocytosis and following intracellular protein processing.

Epidermal Growth Factor, Biotinylated, complexed to Alexa Fluor™ 555 Streptavidin (Alexa Fluor™ 555 EGF complex) (Invitrogen™)

We offer several conjugates of epidermal growth factor that are useful for the detection of EGF receptor in cells. Fluorescently labeled EGF has enabled scientists to investigate receptor-membrane interactions, study receptor distribution, calculate rate constants for the interaction of EGF with its receptor, and more. The conjugates incorporating fluorescein (FITC), Oregon Green® 514, and tetramethylrhodamine were constructed with the dye directly attached to EGF. The conjugates of EGF with Alexa Fluor® dyes and Texas Red® dye are complexes of the dye–streptavidin molecule and biotinylated EGF. The biotinylated conjugates utilize biotin-XX, which contains a long spacer arm designed to enhance the probe’s affinity for the EGF receptor.

Epidermal Growth Factor Conjugate Specifications:
• EGF molecule: 53 amino acids, MW=6,045 Da
• Label (Ex/Em): Biotin-XX complexed with Alexa Fluor® 555 streptavidin (~555/565 nm)
• Number of fluorophore molecules on each EGF molecule: ~2–3
• Fluorescence is typically monitored using a flow cytometer, fluorescence microscope, or fluorimeter


Find More Receptor Binding and Phagocytosis Probes
We offer a number of fluorescently labeled probes for studying receptor-mediated endocytosis, membrane markers for endocytosis and exocytosis, and methods for detecting internalized fluorescent ligands. Review Probes for Following Receptor Binding and Phagocytosis—Section 16.1 in the Molecular Probes® Handbook for more information on these products.

For Research Use. Not for human or animal therapeutic or diagnostic use.

Albumin from Bovine Serum (BSA), Alexa Fluor™ 680 conjugate (Invitrogen™)

This albumin from bovine serum (BSA), Alexa Fluor® 680 conjugate is a bright and photostable conjugate exceptionally suited for applications in which well-defined molecular weight tracers are needed. These applications include studying the rate of endocytosis and exocytosis and following intracellular protein processing.

CaptureSelect™ Biotin Anti-IgG-Fc (Human) Conjugate (Thermo Scientific™)

CaptureSelect™ Biotin Anti-IgG-Fc (Hu) Conjugate consists of a 13 kDa llama antibody fragment (affinity ligand) that specifically binds to the Fc part (CH3 domain) of all four human IgG subclasses. The affinity ligand is chemically conjugated to biotin via an appropriate spacer that retains the binding reactivity of the ligand when used in combination with streptavidin-based conjugates or streptavidin pre-coated surfaces.

The CaptureSelect™ Biotin Anti-IgG-Fc (Hu) Conjugate allows you to:

Detect, quantitate, and characterize all human IgG antibodies (subclasses 1 to 4), recombinant human IgG antibodies, human IgG-derived Fc-fusion proteins including CH2 deleted (or mutated) Fc formats, and total IgG in human plasma and/or serum samples
Avoid cross-binding with other isotypes, such as IgA, IgM, IgD, and IgE, free light chains, or IgG antibodies from non-primate species (for example, bovine, horse, and murine)

Applications for CaptureSelect™ Biotin Anti-IgG-Fc (Hu) Conjugate include ELISA, Western blot, Gyrolab™-based immunoassays, and label-free detection platforms such as those based on surface plasmon resonance (Biacore™ and IBIS-MX96 systems) and bio-layer interferometry (ForteBio™ Octet™ systems).

Annexin V, Pacific Blue™ conjugate, for flow cytometry (Invitrogen™)

Annexin V has a high affinity for phosphatidylserine (PS), which becomes exposed on the outer leaflet of cells undergoing apoptosis. Because of this affinity, fluorescently labeled annexin V reagents are commonly used in apoptosis research. The annexin V, Pacific Blue™ conjugate is violet excitable, making it ideal for instruments with a violet laser and for multicolor experiments that include green- or red-fluorescent dyes.

View a selection guide for all annexin V conjugates for flow cytometry.

Use with the Annexin Binding Buffer for flow cytometry.

CaptureSelect™ Biotin Anti-IgA Conjugate (Thermo Scientific™)

CaptureSelect™ Biotin Anti-IgA Conjugate consists of a 14 kDa llama antibody fragment (affinity ligand) that specifically binds to the α-chain of all human IgA antibodies (Fc domain). The affinity ligand is chemically conjugated to biotin via an appropriate spacer that retains the binding reactivity of the ligand when used in combination with streptavidin-based conjugates or streptavidin pre-coated surfaces.

The CaptureSelect™ Biotin Anti-IgA Conjugate allows you to:

Detect, quantitate, and characterize all human IgA antibodies, including monomeric IgA-1 and IgA-2, dimeric IgA (secretory and non-secretory), and recombinant IgA monoclonal antibodies, as well as total IgA in human plasma and/or serum samples
Avoid cross-binding with other isotypes, such as IgG, IgM, IgD, and IgE, free light chains, or IgA from bovine sources such as FCS

Applications for CaptureSelect™ Biotin Anti-IgA Conjugate include ELISA, Western blot, Gyrolab™-based immunoassays, and label-free detection platforms such as those based on surface plasmon resonance (Biacore™ and IBIS-MX96 systems) and bio-layer interferometry (ForteBio™ Octet™ systems).

Cholera Toxin Subunit B (Recombinant), Alexa Fluor™ 594 Conjugate (Invitrogen™)

Molecular Probes® cholera toxin conjugates are made from a recombinant version of the B subunit only. This allows us to provide a very high-purity product that is completely free of the toxic A subunit. Cholera toxin B subunit (CT-B) attaches to cells by binding to ganglioside GM1, making it a powerful tool for retrograde labeling of neurons. This tracer has been used in a variety of applications, including tracing of rat forebrain afferents, projections of the parabrachial region, and neurons of the urinary bladder wall. When used in neuronal tracing applications, CT-B is typically introduced by pressure injection or by iontophoretic injection into neural tissue.

Cholera Toxin Subunit B Specifications:
• Label (Ex/Em): Alexa Fluor® 594 (590/617 nm)
• At neutral pH, the 11.4 kDa B subunit exists as a 57 kDa pentamer
• Lyophilized product can be dissolved in buffer (e.g., PBS) for use


Cholera Toxin Subunit B for Studying Lipid Rafts
More recently, researchers have found that CT-B can be used as a marker for lipid rafts, which are membrane microdomains enriched in cholesterol and sphingolipids thought to be important in cell signaling. For lipid raft staining, cells are first incubated with fluorescent CT-B. Then, an anti–CT-B antibody is added to crosslink the CT-B in the lipid rafts into distinct patches on the plasma membrane. These patches are easily visualized by fluorescence microscopy. In addition to individual fluorescent CT-B conjugates, we also offer Vybrant® Lipid Raft Labeling Kits that contain the Alexa Fluor® 488, Alexa Fluor® 555, or Alexa Fluor® 594 dye conjugates of CT-B, an anti–CT-B antibody, and a detailed protocol for labeling and preparing cells for fluorescence microscopy.

Find More CT-B Conjugates
We offer various CT-B conjugates. Review Protein Conjugates—Section 14.7 in the Molecular Probes® Handbook for more information on these tracers.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.