Regulation of the mouse retinal taurine transporter (TAUT) by protein kinases in Xenopus oocytes.
The goal was to investigate the role of protein kinases in modulating taurine transporter activity in Xenopus laevis oocytes expressing the mouse retinal Na+/C-/taurine transporter. The currents generated by the taurine transporter were studied with a two-electrode voltage clamp and we recorded the maximal current (Imax), presteady-state charge transfer Q, and membrane capacitance Cm. 8-Br-cAMP, a membrane-permeable activator of the cAMP-dependent protein kinase (PKA), decreased Imax (41%), Q (41%) and Cm (10%). Similarly, 1 microM sn-1,2-dioctanoylglycerol (DOG), an activator of the Ca2+/diacylglycerol-dependent protein kinase (PKC), decreased Imax (56%), Q (37%), and Cm (9%). Calyculin A, a specific inhibitor of protein phosphatases 1 and 2A, also produced effects similar to those of 8-Br-cAMP and DOG, and decreased Imax (64 %), Q (38%), and Cm (10%). We conclude that the taurine transporter is regulated by activators of PKA and PKC, and regulation occurs largely by changes in the number of transporters in the plasma membrane.
Loo
D D
DD
Department of Physiology, UCLA School of Medicine, Center for the Health Sciences, Los Angeles, CA 90095-1751, USA.
Hirsch
J R
JR
Sarkar
H K
HK
Wright
E M
EM
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000187:drug effects / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology; D004594:Electrophysiology / Q000379:methods; D004705:Endocytosis / Q000502:physiology; D004789:Enzyme Activation; D005089:Exocytosis / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation; D008387:Marine Toxins; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000502:physiology*; D026901:Membrane Transport Proteins; D051379:Mice; D009865:Oocytes / Q000378:metabolism* / Q000502:physiology; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012160:Retina / Q000737:chemistry*; D012964:Sodium / Q000378:metabolism; D014982:Xenopus laevis; D000099247:Taurine Transporters
D015124:8-Bromo Cyclic Adenosine Monophosphate; D002352:Carrier Proteins; D002712:Chlorides; D017868:Cyclic AMP-Dependent Protein Kinases; D004075:Diglycerides; D008387:Marine Toxins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D010080:Oxazoles; D010749:Phosphoprotein Phosphatases; D011493:Protein Kinase C; D011994:Recombinant Proteins; D012964:Sodium; D000099247:Taurine Transporters; C044295:1,2-dioctanoylglycerol; C059041:calyculin A