EVIDENCE THAT THE RAT HEPATIC MITOCHONDRIAL CARRIER IS DISTINCT FROM THE SINUSOIDAL AND CANALICULAR TRANSPORTERS FOR REDUCED GLUTATHIONE - EXPRESSION STUDIES IN XENOPUS-LAEVIS OOCYTES
C. Garciaruiz et al., EVIDENCE THAT THE RAT HEPATIC MITOCHONDRIAL CARRIER IS DISTINCT FROM THE SINUSOIDAL AND CANALICULAR TRANSPORTERS FOR REDUCED GLUTATHIONE - EXPRESSION STUDIES IN XENOPUS-LAEVIS OOCYTES, The Journal of biological chemistry, 270(27), 1995, pp. 15946-15949
Mitochondrial GSH derives hom a mitochondrial transport system (RmGshT
), which translocates cytosol GSH into the mitochondrial matrix. Mitoc
hondria of oocytes, isolated 3-4 days after microinjection of total li
ver mRNA, expressed a RmGshT compared with water-injected oocytes, The
expressed RmGshT exhibited similar functional features as reported in
isolated mitochondria of rat liver such as ATP stimulation, inhibitio
n by glutamate, and insensitivity to inhibition by sulfobromophthalein
-glutathione (BSP-GSH) and S-(2,4-dinitrophenyl)glutathione (DNP-GSH).
The expressed RmGshT is localized in the inner mitochondrial membrane
since expression is still observed in mitoplasts prepared from total
liver mRNA-injected oocytes. Fractionation of poly(A)(+) RNA identifie
d a single mRNA species of similar to 3-3.5 kilobases encoding for the
RmGshT, which was stimulated by ATP and inhibited by glutamate but no
t by BSP-GSH or DNP-GSH, Microinjection of this fraction did not lead
to expression of plasma membrane GSH transport in intact oocytes, and
conversely, oocytes microinjected with cRNA for rat liver sinusoidal G
SH transporter (RsGshT) or rat liver canalicular GSH transporter (RcGs
hT) did not express mitochondrial GSH transport activity. Thus, our re
sults show the successful expression of the rat hepatic mitochondrial
GSH carrier, which is different from RsGshT and RcGshT, and provide th
e strategic basis for the cloning of this important carrier.