Na+ + Cl- -gradient-driven, high-affinity, uphill transport of taurine in human placental brush-border membrane vesicles.
Uptake of taurine in human placental brush-border membrane vesicles was greatly stimulated in the presence of an inwardly-directed Na+ + Cl- -gradient and uphill transport of taurine could be demonstrated under these conditions. Na+ as well as Cl- were obligatory for this uptake and both ion gradients could energize the uphill transport. This Na+ + Cl- -gradient-dependent taurine uptake was stimulated by an inside-negative membrane potential, demonstrating the electrogenicity of the process. The uptake system was highly specific for beta-amino acids and the Km of the system for taurine was 6.5 +/- 0.4 microM.
Miyamoto
Y
Y
Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.
Balkovetz
D F
DF
Leibach
F H
FH
Mahesh
V B
VB
Ganapathy
V
V
D001692:Biological Transport / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012964:Sodium / Q000494:pharmacology*; D013654:Taurine / Q000378:metabolism*; D014634:Valinomycin / Q000494:pharmacology
D002712:Chlorides; D013654:Taurine; D014634:Valinomycin; D012964:Sodium