Shop All Protein Conjugates

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.

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.

Pierce™ Bovine Serum Albumin, Biotinylated (Thermo Scientific™)

Thermo Scientific Pierce Biotinylated Proteins include biotin-labeled proteins (BSA), enzymes (HRP, AP) and fluorophores (FITC) for use as controls or signal amplification in IHC via avidin-biotin complex (ABC) techniques.

Biotinylated controls—use biotinylated bovine serum albumin (B-BSA) as a positive control in biotin quantitation methods

Biotin, also known as vitamin H, is a small molecule (MW 244.3) that is present in tiny amounts in all living cells and is critical for a number of biological processes. The valeric acid side chain of the biotin molecule can be derivatized in order to incorporate various reactive groups that are used to attach biotin to other molecules. In the context of immunohistochemistry (IHC), biotin is conjugated to antibodies or to the enzyme reporters used to detect target antigens.

Related Products
Pierce™ Horseradish Peroxidase, Biotinylated
Pierce™ Alkaline Phosphatase, Biotinylated
Pierce™ Biotin-Fluorescein Conjugate
Pierce™ Biotin

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.

Transferrin From Human Serum, Alexa Fluor™ 594 Conjugate (Invitrogen™)

Transferrin is a monomeric serum glycoprotein (~80,000 daltons) that binds to a specific receptor on the surface of vertebrate cells and delivers up to two Fe3+ atoms via receptor-mediated endocytosis—our labeled LDL complexes are useful tools for studying this phenomenon. Once iron-carrying transferrin proteins are inside endosomes, the acidic environment favors dissociation of iron from the transferrin–receptor complex. Following the release of iron, the apotransferrin is recycled to the plasma membrane, where it is released from its receptor to scavenge more iron. Fluorescent transferrin conjugates can therefore be used with fluorescent LDL to distinguish the lysosomally directed and recycling endosomal pathways.

These experiments are typically performed by adding fluorescently labeled transferrin to cultured cells and analyzing them by microscopy. We offer a biotinylated transferrin conjugate and more than 10 fluorescent versions.

Transferrin Specifications:

Label (Ex/Em): Alexa Fluor® 594 (590/617)

Amount: 15 mg solid (contains 5 mg of transferrin conjugate)

Key Applications of Labeled Transferrin
Some of the many applications for labeled transferrin include:
• Image transferrin receptor dynamics using FRET
• Observe receptor trafficking in live cells by confocal laser-scanning microscopy
• Investigate events occurring during endosomal acidification
• Measure transferrin receptor binding affinity in mammals and parasites

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.

Pierce™ Horseradish Peroxidase, Biotinylated (Thermo Scientific™)

Thermo Scientific Pierce Biotinylated Proteins include biotin-labeled proteins (BSA), enzymes (HRP, AP) and fluorophores (FITC) for use as controls or signal amplification in IHC via avidin-biotin complex (ABC) techniques.

Biotinylated HRP is most commonly used in immunohistochemistry (IHC) to amplify the signal of biotinylated primary antibodies using the ABC staining method.

Biotinylated enzymes—biotin-labeled horseradish peroxidase (B-HRP), alkaline phosphatase (B-AP) and beta-galactosidase (B-bGal) for use in avidin-biotin complex (ABC) staining

Biotin, also known as vitamin H, is a small molecule (MW 244.3) that is present in tiny amounts in all living cells and is critical for a number of biological processes. The valeric acid side chain of the biotin molecule can be derivatized in order to incorporate various reactive groups that are used to attach biotin to other molecules. In the context of immunohistochemistry (IHC), biotin is conjugated to antibodies or to the enzyme reporters used to detect target antigens.

Related Products
Pierce™ Bovine Serum Albumin, Biotinylated
Pierce™ Alkaline Phosphatase, Biotinylated
Pierce™ Biotin-Fluorescein Conjugate
Pierce™ Biotin

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.

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.

Epidermal Growth Factor, Biotinylated, complexed to Alexa Fluor™ 647 Streptavidin (Alexa Fluor™ 647 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® 647 streptavidin (~650/665 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.

Pierce™ Alkaline Phosphatase, Biotinylated (Thermo Scientific™)

Thermo Scientific Pierce Biotinylated Proteins include biotin-labeled proteins (BSA), enzymes (HRP, AP) and fluorophores (FITC) for use as controls or signal amplification in IHC via avidin-biotin complex (ABC) techniques.

Biotinylated AP is most commonly used in immunohistochemistry (IHC) to amplify the signal of biotinylated primary antibodies using the ABC staining method.

Biotinylated enzymes—biotin-labeled horseradish peroxidase (B-HRP), alkaline phosphatase (B-AP) and beta-galactosidase (B-bGal) for use in avidin-biotin complex (ABC) staining

Biotin, also known as vitamin H, is a small molecule (MW 244.3) that is present in tiny amounts in all living cells and is critical for a number of biological processes. The valeric acid side chain of the biotin molecule can be derivatized in order to incorporate various reactive groups that are used to attach biotin to other molecules. In the context of immunohistochemistry (IHC), biotin is conjugated to antibodies or to the enzyme reporters used to detect target antigens.

Related Products
Pierce™ Bovine Serum Albumin, Biotinylated
Pierce™ Horseradish Peroxidase, Biotinylated
Pierce™ Biotin-Fluorescein Conjugate
Pierce™ Biotin

Actin, from rabbit muscle, Alexa Fluor™ 568 conjugate, in solution (Invitrogen™)

The orange-fluorescent Alexa Fluor® 568 actin conjugate is an important tool for investigating cytoskeleton dynamics in-vivo. This fluorescent conjugate is prepared by labeling the amine residues of polymerized F-actin. After labeling, the conjugates are subjected to depolymerization and subsequent polymerization to ensure that the actin conjugates are able to assemble properly. The labeled actin that polymerizes is then separated from remaining monomeric actin by centrifugation, depolymerized and packaged in monomeric form.

Cholera Toxin Subunit B (Recombinant), Alexa Fluor™ 647 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® 647 (650/668 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.

α-Bungarotoxin, Alexa Fluor™ 555 conjugate (Invitrogen™)

α-Bungarotoxin, a 74-amino acid peptide extracted from Bungarus multicinctus venom, binds with high affinity to the α-subunit of the nicotinic acetylcholine receptor (AChR) of neuromuscular junctions. Our bright and photostable Alexa Fluor® 555 alpha-bungarotoxin may prove to be one of the best probes for visualizing this receptor. Fluorescent α-bungarotoxin conjugates can be used to facilitate identification of nicotinic AChRs and to localize neuromuscular junctions.

Transferrin From Human Serum, Alexa Fluor™ 555 Conjugate (Invitrogen™)

Transferrin is a monomeric serum glycoprotein (~80,000 daltons) that binds to a specific receptor on the surface of vertebrate cells and delivers up to two Fe3+ atoms via receptor-mediated endocytosis—our labeled LDL complexes are useful tools for studying this phenomenon. Once iron-carrying transferrin proteins are inside endosomes, the acidic environment favors dissociation of iron from the transferrin–receptor complex. Following the release of iron, the apotransferrin is recycled to the plasma membrane, where it is released from its receptor to scavenge more iron. Fluorescent transferrin conjugates can therefore be used with fluorescent LDL to distinguish the lysosomally directed and recycling endosomal pathways.

These experiments are typically performed by adding fluorescently labeled transferrin to cultured cells and analyzing them by microscopy. We offer a biotinylated transferrin conjugate and more than 10 fluorescent versions.

Transferrin Specifications:

Label (Ex/Em): Alexa Fluor® 555 (555/565)

Amount: 15 mg solid (contains 5 mg of transferrin conjugate)

Key Applications of Labeled Transferrin
Some of the many applications for labeled transferrin include:
• Image transferrin receptor dynamics using FRET
• Observe receptor trafficking in live cells by confocal laser-scanning microscopy
• Investigate events occurring during endosomal acidification
• Measure transferrin receptor binding affinity in mammals and parasites

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