Monitoring Editor: Sandra Schmid Sodium-dependent neurotransmitter transporters participate in the clearance and/or recycling of neurotransmitters from synaptic clefts. The
snf-11 gene in C. elegans encodes a protein of high similarity to mammalian GABA transporters (GATs). We show here that
snf-11 encodes a functional GABA transporter; SNF-11-mediated GABA transport is Na(+)- and Cl(-)-dependent, has an EC50 of 168 microM, and is blocked by the GAT1 inhibitor SKF89976A. The SNF-11 protein is expressed in seven GABAergic neurons, several additional neurons in the head and retrovesicular ganglion, and three groups of muscle cells. Therefore, all GABAergic synapses are associated with either presynaptic or post-synaptic (or both) expression of SNF-11. Although a
snf-11 null mutation has no obvious effects on GABAergic behaviors, it leads to resistance to inhibitors of acetylcholinesterase. In vivo, a
snf-11 null mutation blocks GABA uptake in at least a subset of GABAergic cells; in a cell culture system, all GABA uptake is abolished by the
snf-11 mutation. We conclude that GABA transport activity is not essential for normal GABAergic function in C. elegans; and the localization of SNF-11 is consistent with a GABA clearance function rather than recycling.