Functional characterization of the GABA transporter GAT-1 from the deep-sea mussel Bathymodiolus septemdierum.
Comp Biochem Physiol A Mol Integr Physiol
; 227: 1-7, 2019 01.
Article
en En
| MEDLINE
| ID: mdl-30195015
ABSTRACT
Mammalian γ-aminobutyric acid (GABA) transporter subtype 1 (GAT-1) is a specific transporter for GABA, an inhibitory neurotransmitter in GABA-ergic neurons. GAT-1 belongs to the GAT group, in which five related transporters, GAT-2, GAT-3, GAT-4, CT1, and TAUT are known in mammals. By contrast, the deep-sea mussel, Bathymodiolus septemdierum has only two GAT group members, BsGAT-1 and BsTAUT, and their function in environmental adaptation is of interest to better understand the physiology of deep-sea organisms. Compared with BsTAUT, the function of BsGAT-1 is unknown. Here, we report the functional characterization of BsGAT-1. Analyses of BsGAT-1 expressed in Xenopus oocytes showed that it could transport GABA in a Na+- and Cl--dependent manner, with Km and Vmax values of 0.58⯵M and 1.97â¯pmol/oocyte/h, respectively. BsGAT-1 activity was blocked by the GAT-1 selective inhibitors SKF89976A and ACHC. Competition assays indicated that BsGAT-1 has no affinity for taurine and thiotaurine. These characteristics were common with those of mammalian GAT-1, suggesting its conserved function in the nervous system. However, BsGAT-1 showed a certain affinity for hypotaurine, which is involved in sulfide detoxification in hydrothermal vent-specific animals. This result suggests an additional role for BsGAT-1 in sulfide detoxification, which may be specific to the deep-sea mussel. In a tissue distribution analysis, BsGAT-1 mRNA expression was observed in various tissues. The expression in the adductor and byssus retractor muscles, labial palp, and foot, which possibly contain ganglia, suggested a function in the neural system, while BsGAT-1 expression in other tissues might be related to sulfide detoxification.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Mytilidae
/
Proteínas Transportadoras de GABA en la Membrana Plasmática
Límite:
Animals
Idioma:
En
Revista:
Comp Biochem Physiol A Mol Integr Physiol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
FISIOLOGIA
Año:
2019
Tipo del documento:
Article