Transporter tandems: precise tools for normalizing active transporter in the plasma membrane.

The transport efficiency (TE) describes the performance of a transport protein for a specific substrate. To compare the TE of different transporters, the number of active transporters in the plasma membrane must be monitored, as it may vary for each transporter and experiment. Available methods, like LC-MS quantification of tryptic peptides, fail to discriminate inactive intracellular transporters or, like cell-surface biotinylation followed by affinity chromatography and Western blotting, are imprecise and very laborious.

Substrate Selectivity Check of the Ergothioneine Transporter.

The candidate vitamin ergothioneine (ET) is a unique antioxidant. Expression of the ET transporter (ETT) (gene symbol ) in distinct cells is thought to signal intracellular ET activity, since we have previously shown that the ETT is highly selective for ET. Unfortunately, some continue to hold the ETT as a relevant drug transporter, using the misleading functional name OCTN1, novel organic cation transporter.