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gamma-aminobutyrate permease GABA permease (gabP) catalyzes the translocation of 4-aminobutyrate (GABA) across the plasma membrane, with homologues expressed in Gram-negative and Gram-positive organisms. This permease is a highly hydrophobic transmembrane protein consisting of 12 transmembrane domains with hydrophilic N- and C-terminal ends. Induced by nitrogen-limited culture conditions in both Escherichia coli and Bacillus subtilis, gabP is an energy dependent transport system stimulated by membrane potential and has been observed adjacent and distant from other GABA degradation proteins. GabP is highly homologous to amino acid permeases from B. subtilis, E. coli, as well as to other members of the amino acid permease family (pfam00324). A member of the APC (amine-polyamine-choline) transporter superfamily, GABA permease possesses a "consensus amphiphatic region" (CAR) found to be evolutionarily conserved within this transport family. This amphiphatic region is located between helix 8 and cytoplasmic loop 8-9, forming a potential channel domain and suggested to play a significant role in ligand recognition and translocation. Unique to GABA permeases, a conserved cysteine residue (CYS-300, E.coli) located at the beginning of the amphiphatic domain, has been determined to be critical for catalytic specificity. [Transport and binding proteins, Amino acids, peptides and amines] |
Jiyao W et al.(2023). "The conserved domain database in 2023.",