Cloning and Expression of a Rat Brain GABA Transporter

TLDR

Hydropathy analysis indicates multiple transmembrane domains, but GAT‑1 shows no homology to known proteins. The cloned GAT‑1 cDNA encodes a 599‑amino‑acid, 67‑kDa GABA transporter that functions in Xenopus oocytes with high affinity, sodium‑ and chloride‑dependence, and pharmacological similarity to neuronal transporters, and represents a novel, previously uncharacterized family of transport molecules.

Abstract

A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter γ-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in Xenopus oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated [ 3 H]GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium-and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters. The GAT-1 protein shares antigenic determinants with a native rat brain GABA transporter. The nucleotide sequence of GAT-1 predicts a protein of 599 amino acids with a molecular weight of 67 kilodaltons. Hydropathy analysis of the deduced protein suggests multiple transmembrane regions, a feature shared by several cloned transporters; however, database searches indicate that GAT-1 is not homologous to any previously identified proteins. Therefore, GAT-1 appears to be a member of a previously uncharacterized family of transport molecules.