Sodium- and chloride-dependent glycine transporter which is essential for regulating glycine concentrations at inhibitory glycinergic synapses. chloride(out) + glycine(out) + 2 Na(+)(out) = chloride(in) + glycine(in) + 2 Na(+)(in) Interacts with EXOC1; interaction increases the transporter capacity of SLC6A9 probably by promoting its insertion into the cell membrane (By similarity). Interacts with EXOC3 and EXOC4 (By similarity). Belongs to the sodium:neurotransmitter symporter (SNF) (TC 2.A.22) family. SLC6A9 subfamily.