{"id":2913,"date":"2026-08-22T15:49:38","date_gmt":"2026-08-22T14:49:38","guid":{"rendered":"https:\/\/seamlessbio.de\/?page_id=2913"},"modified":"2026-08-23T00:55:29","modified_gmt":"2026-08-22T23:55:29","slug":"what-is-vesicular-transport-assay","status":"publish","type":"page","link":"https:\/\/seamlessbio.de\/de\/what-is-vesicular-transport-assay\/","title":{"rendered":"What is a Vesicular Transport Assay"},"content":{"rendered":"
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Quick Definition<\/p>\n

What is a Vesicular Transport Assay?:<\/strong> A vesicular transport assay is an in vitro method for measuring ABC transporter activity using inside-out membrane vesicles \u2014 sealed membrane fragments where the cytoplasmic face of the transporter is exposed outward. When ATP is added, the transporter pumps its substrate into the vesicle interior, allowing direct quantification of substrate accumulation and inhibitor IC50 determination.<\/p>\n<\/div>\n\n

Why inside-out?<\/h2>\n

ABC efflux transporters in living cells have their substrate-binding site facing the cytoplasm \u2014 inaccessible from outside the cell. To study the transporter directly, the membrane must be inverted. In inside-out vesicles, the binding site faces the incubation buffer, allowing the test compound to interact with the transporter without first crossing a cell membrane. This eliminates passive permeability as a confounding variable \u2014 the major limitation of cell-based transport assays for lipophilic compounds.<\/p>\n\n

Vesicular transport vs cell-based assay<\/h2>\n

Cell-based bidirectional transport assays (Caco-2, MDCKII-MDR1) measure the efflux ratio of a compound across a cell monolayer. For high-permeability compounds, passive diffusion dominates and the efflux ratio collapses toward 1.0 \u2014 masking active transporter efflux. The vesicular transport assay has no such limitation because no membrane crossing is required to reach the transporter binding site.<\/p>\n\n

Ready-to-use vesicle kits<\/h2>\n

Cell4Pharma ABC Transporter Vesicle Kits (distributed by SeamlessBio in DACH) provide pre-prepared, QC-validated inside-out membrane vesicles for in-house DMPK transporter testing \u2014 covering BSEP, P-gp, BCRP, MRP1\u2013MRP5, MRP8, and Control vesicles. 100 reactions per kit, stored at \u221280\u00b0C.<\/p>\n\n

Key Facts<\/h2>\n