Product manual
Product use, preparation, operating conditions and storage.
Cy5.5Bioconjugate
Cy5.5 CTB
Cat. No.QH-30-3004(CTB)
Use CTB binding to GM1 for fluorescence localization in surface-binding and uptake/trafficking studies.
Packs & quoteCTB
Fluorescent conjugateGM1
GM1 gangliosideBinding
Noncovalent recognitionExcitation680 nm
Emission698 nm
TargetAccessible ganglioside GM1
Preparation and storage
- Preparation
- Aqueous formulation
- Storage
- Store at 2–8°C, protect from light. Do not freeze
CTB–GM1 binding
CTB is the cholera toxin B subunit and binds GM1 multivalently. The probe can alter GM1 clustering and membrane behavior, so CTB signal alone does not establish lipid-raft number or membrane-domain structure.
GM1-associated localization
Observe accessible surface GM1 and assess spatial distribution with independent markers.
Binding and uptake tracking
Use timed acquisition to distinguish initial surface binding from later trafficking, recording temperature and chase time.
Specifications
Product information
- Product name
- Cy5.5 CTB
- Cat. No.
- QH-30-3004(CTB)
- Product form
- CTB
- Target
- Accessible ganglioside GM1
- Pack sizes
- 1 mg / 5 mg / 10 mg / 25 mg / 100 mg
Preparation and properties
- Excitation wavelength
- 680 nm
- Emission wavelength
- 698 nm
- Molar extinction coefficient
- 198,000 M⁻¹ cm⁻¹
- Quantum yield
- 0.2
- Preparation and sample
- Aqueous formulation
- Storage
- Store at 2–8°C, protect from light. Do not freeze
Spectral information and detection
Product parameters
Use parameters for the exact catalog number when preparing reagents, setting reagent input or calculating results. Request a lot-specific CoA for test results.
Protocol
Define the endpoint
Distinguish surface binding, uptake and tissue tracing. Establish concentration, timing and sample preparation separately for each application.
Formulation and dilution
Handle the protein conjugate in a suitable aqueous buffer; do not treat CTB as a small reactive dye requiring DMSO activation.
Prepare controls and titration
Include an unstained sample and probe titration, recording cell density and processing.
Bind and chase
Follow defined binding, wash and chase times. Match acquisition settings when comparing surface and intracellular signal.
Analyze localization
Use independent localization markers and a time series to assess clustering, nonspecific background and concentration effects.
Request product documentation
Select a document and enter your phone and email. Include the lot number for a CoA.
Cy5.5 CTBQH-30-3004(CTB)
Spectra and measurement conditions
Spectra, measurement conditions and detection settings for the exact catalog number.
Certificate of analysis (CoA)
Lot-specific test results. Include the lot number from the vial.
Safety data sheet (SDS)
Handling, storage and emergency response information.
Quality and lot information
Unstained and single-stain controls
Assess autofluorescence, detection channels and compensation or unmixing.
Time and temperature controls
Compare initial binding with chase endpoints so internalized puncta are not mistaken for the original membrane organization.
Probe perturbation
Compare low and high amounts with independent localization data to assess clustering caused by multivalent CTB binding.
Technical articles
CTB signal and lipid raft interpretation
CTB fluorescence reports GM1-associated distribution; puncta alone do not establish native lipid-raft structure.
For CTB–GM1 localization, including perturbation of membrane organization by multivalent binding.
Time-course analysis of CTB binding and uptake
Distinguish peripheral and intracellular CTB signals over time; one endpoint cannot establish a trafficking route.
For CTB surface binding and trafficking; total intensity alone does not quantify uptake.
Application support
Include your sample, formulation and detection method when requesting application guidance.
References
Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin
Kabbani AM, Raghunathan K, Lencer WI, Kenworthy AK, Kelly CV. · PNAS · 117(26):14978–14986 · 2020
Examines how multivalent CTB binding affects GM1 organization and membrane shape, highlighting probe-induced perturbation.
Frequently asked questions
Does CTB positivity identify lipid rafts?
CTB signal reflects accessible GM1 and probe binding; membrane domains require independent evidence.
Is it suitable for every neuronal tracing experiment?
Tracing depends on tissue, administration and timing. Validate the formulation in the intended model.
Is further conjugation needed?
The fluorophore is already conjugated. Follow protein-probe staining and storage requirements.