The Choline Transporter Resurfaces: New Roles for Synaptic Vesicles?

CHT accumulates on the plasma membrane when constitutive endocytosis is impaired. (A) We have observed that cotransfection of COS-7 cells with hCHT plus the dominant negative K44A mutant of dynamin I (127) elicits 15.6 +/– 1.1 fold more HC-3 sensitive [³ H]-choline uptake than cotransfection of hCHT with an empty vector control. (All assays performed in triplicate, n = 3, p < 0.0005.) (B) Cell surface biotinylation confirms that hCHT accumulates on the plasma membrane when clathrin-mediated endocytosis is blocked by expression of the K44A mutant of dynamin I.