The pentameric ring of the B subunit of cholera enterotoxin (CtxB) guides the A subunit to its target by binding to monosialotetrahexosylganglioside (GM1) gangliosides on the surface of intestinal epithelial cells. Each CtxB pentamer can bind up to five GM1 molecules but exhibits no intrinsic toxic activity. Recent findings indicate that human extracellular vehicles (EVs), which are enriched with GM1 gangliosides on their surface, can be selectively captured from unconcentrated body fluids using microplate wells coated with CtxB. This approach also facilitates the use of sfGFP-CtxB fusion protein as a detecting reagent for tracing EVs in various biological samples.

Full-length mature form of cholera enterotoxin subunit B cDNA (104aa) was constructed with codon optimization gene synthesis and expressed with a SuperGFP Protein N-terminal (sfGFP; 257aa) fusion at target protein N-terminal in E.coli as soluble protein. The final product was affinity - column purified.

A T Aman et al., A mutant cholera toxin B subunit that binds GM1- ganglioside but lacks immunomodulatory or toxic activity. PNAS Jul 10;98(15):8536–8541 (2001) 

Willian A Walker, et al., Cellular Endocytosis and Trafficking of Cholera Toxin B-Modified Mesoporous Silica Nanoparticles. J Mater Chem B. Jan 7;4(7):1254–1262 (2016)

1. May be used as capture reagents for human EV studying either for plate/well based assay or magnetic beads based assay. 
2. May be used as tracking reagent for endocytosis study, such as Mesoporous Silica Nanoparticle coated beads assay

Purity: > 91% by SDS-PAGE.

sfGFP protein: Ex λ = 485nm, and Em λ = 510nm.

MKHHHHHHQVSKGEELFTGVVPILVELDGDVNGHKFSVRGEGEGDATNGKLTLKFICTTGKLPVPWPTLVTTLTYGVQCFSRYPDHMKRHDFFKSAMPEGYVQERTISFKDDGTYKTRAEVKFEGDTLVNRIELKGIDFKEDGNILGHKLEYNFNSHNVYITADKQKNGIKANFKIRHNVEDGSVQLADHYQQNTPIGDGPVLLPDNHYLSTQSVLSKDPNEKRDHMVLLEFVTAAGITHGMDELYKSGLRSGGSGGENLYFQGSEFTPQNITDLCAEYHNTQIYTLNDKIFSYTESLAGKREMAIITFKNGAIFQVEVPGSQHIDSQKKAIERMKDTLRIAYLTEAKVEKLCVWNNKTPHAIAAISMAN

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