Phorbol-ester is bound specifically to renal luminal membranes and stimulates the Na-H antiporter.
We characterized binding of [3H]-phorbol-12,13-dibutyrate (an activator of protein kinase C) to highly purified rabbit cortical renal luminal membranes and measured its effect on the kinetics of the Na-H antiporter. There was 95% specific binding to luminal membranes and this binding was time, temperature and pH dependent with optimal binding at 4 degrees C and pH 7.4. Scatchard analysis of the binding revealed Kd of 0.8 microM and Bmax of 19.4 pmoles/mg protein. Phorbol-12,13-dibutyrate stimulated the Vmax of the Na-H antiporter by 16.5% +/- 4.7 at 10(-6) M and by 19.9% +/- 5.4 at 10(-5) M. The protein kinase C inhibitor H7(1) prevented the observed stimulation. Thus, there is a correlation between phorbol ester binding and phorbol ester stimulation of the Na-H antiporter. These data demonstrate that protein kinase C plays a role in the stimulation of the Na-H antiporter in renal luminal membranes.
Talor
Z
Z
Section of Nephrology, University of Illinois, Chicago.
Mejicano
G C
GC
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008566:Membranes / Q000378:metabolism; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism* / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011817:Rabbits; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C