Specificity of the rat vesicular acetylcholine transporter.

The protein kinase A-deficient PC12 cell line PC12A123.7 lacks both choline acetyltransferase and the vesicular acetylcholine transporter. This cell line has been used to establish a stably transfected cell line expressing recombinant rat vesicular acetylcholine transporter that is appropriately trafficked to small synaptic vesicles. Acetylcholine is transported by the rat vesicular acetylcholine transporter at a maximal rate of 1.45 nmol acetylcholine/min/mg protein and exhibits a Km for transport of 2.5 mM. The transporter binds vesamicol with a Kd of 7.5 nM. The ability of structural analogs of acetylcholine to inhibit both acetylcholine uptake and vesamicol binding was measured. The results demonstrate that like Torpedo vesicular acetylcholine transporter, the mammalian transporter can bind a diverse group of acetylcholine analogs.