Cytosolic Tracers

6-CFDA is membrane-permeant and thus can be loaded into cells via incubation. Once inside cells, 6-CFDA is hydrolyzed by intracellular esterases to 6-carboxyfluorescein.

Biocytin (ε-Biotinoyl-L-lysine) is a very useful cellular tracer that can be introduced into cells by microinjection.

Biotin ethylenediamine in free base form. White solid soluble in DMSO.

Biotin ethylenediamine, hydrobromide (N-(5-(6-((biotinoyl)amino)hexanoyl)amino)pentylmaleimide) is identical to Neurobiotin™, a useful anterograde and transneuronal tracer.

Biotin ethylenediamine, hydrochloride is functionally equivalent to Neurobiotin™ (biotin ethylenediamine, hydrobromide, 90057).

A biotin-conjugated cAMP analog that can be used to probe cAMP receptors.

A biotinylated cyclic nucleotide that is an important second messenger in many biological processes and has been used as a tracer in immunoassays.

Calcein is a highly negatively charged, water-soluble fluorescein derivative. Its fluorescence is nearly independent of pH in the range between 6.5 and 12.

Calcein AM is a widely used green fluorescent cell marker. Calcein AM is membrane-permeant and thus can be introduced into cells via incubation.

5-(and-6)-Carboxy-2′,7′-dichlorofluorescein diacetate is membrane-permeant and thus can be loaded into cells via incubation. The diacetate is readily hydrolyzed to 5-(and-6)-carboxy-2′,7′-dichlorofluorescein (51015) by intracellular esterases.

CF® Dye biocytin is a cell-impermeant, fixable polar tracer that is a conjugate of CF® Dye and biotin with an aldehyde-fixable primary amine. Polar tracers are commonly used to investigate cell-cell and cell-liposome fusion as well as membrane permeability and transport through gap junctions or cell uptake during pinocytosis.

The principle of DPA/Tb³ for vesicle fusion assay is based on the fact that contact of the chelator dipicolinic acid (DPA) with terbium (III) forms an instant Tb³ -DPA complex that is ~10,000 times more fluorescent than free Tb³ . In the assay, separate vesicle populations are loaded with 2.5 mM TbCl3 in 50 mM sodium citrate, or 50 mM DPA in 20 mM NaCl.

DPX is a positively charged quencher that is often used with ANTS (90010) to study membrane fusion or permeability.

Fluorescein biotin (5-((N-(5-(N-(6-(Biotinoyl)amino)hexanoyl)amino)pentyl)thioureidyl) fluorescein) can be used to detect and quantify biotin binding sites and the degree of biotinylation of proteins. Also see biotin-rhodamine 110 (80022) and biotin-4-fluorescein (90062).

Hydroxystilbamidine (also called Fluoro-Gold™) has been used extensively as a retrograde tracer for neurons and also a histochemical stain.

Hydroxystilbamidine (also called Fluoro-Gold™) has been used extensively as a retrograde tracer for neurons and also a histochemical stain. The 4% solution in deionized H₂O is a convenient, ready-made solution.