SEC14-like protein 1 interacts with cholinergic transporters

Trafficking of the vesicular acetylcholine transporter (VAChT) to synaptic vesicles has the potential to regulate storage and release of acetylcholine. We used the C-terminal tail of the vesicular acetylcholine transporter as bait for the screening of a brain cDNA library by yeast-two hybrids. Here we report an interaction uncovered in this screening with SEC14L1, a mammalian SEC14-like protein that may function as a phospholipid transfer protein. The interaction of VAChT and SEC14L1 occurred through the GOLD domain found in the latter and was confirmed in mammalian cells. In addition, we also found that SEC14L1 co-immunoprecipitates with the high affinity choline transporter (CHT1), but not with synaptophysin or synaptotagmin. In cultured cells SEC14L1 was predominantly found in the cytosol with little or no localization in defined organelles. In contrast, overexpression of VAChT or CHT1 with SEC14L1 recruited the latter to large intracellular organelles similar to vesicles or vesicle aggregates. Finally, we find that overexpression of SEC14L1 modestly decreases high affinity choline transport activity. We suggest that interaction of cholinergic transporters with proteins containing the GOLD domain may be relevant for transporter function.