Functional expression of bacteriorhodopsin in oocytes allows direct measurement of voltage dependence of light induced H+ pumping.
We report on the first successful expression of the light driven H+ pump, bacteriorhodopsin, into the plasma membrane of oocytes from Xenopus laevis. The light induced photocurrents which reflect the pumping of H+ by BR were analysed under voltage clamp conditions. At least 100 active BR molecules per microns 2 were expressed in the plasma membrane so that both the voltage clamp and giant patch clamp method could be applied. We show that H+ pumping by BR is modulated by the membrane potential, i.e. the pump current shows strong voltage dependence in the range measured between -165 mV to +60 mV.
Max-Planck-Institut für Biophysik, Frankfurt, Germany.
G
G
Nagel
B
B
Möckel
G
G
Büldt
E
E
Bamberg
D000818:Animals; D001436:Bacteriorhodopsins / Q000737:chemistry / Q000235:genetics*; D004563:Electrochemistry; D008027:Light; D008564:Membrane Potentials; D009865:Oocytes; D018408:Patch-Clamp Techniques; D017494:Proton Pumps / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012172:Retinaldehyde / Q000378:metabolism; D014982:Xenopus laevis
D017494:Proton Pumps; D011994:Recombinant Proteins; D001436:Bacteriorhodopsins; D012172:Retinaldehyde