PlumX Metrics
Embed PlumX Metrics

Passive nitrate transport by root plasma membrane vesicles exhibits an acidic optimal pH like the H-ATPase

Plant Physiology, ISSN: 0032-0889, Vol: 122, Issue: 1, Page: 265-273
2000
  • 13
    Citations
  • 0
    Usage
  • 27
    Captures
  • 0
    Mentions
  • 0
    Social Media
Metric Options:   Counts1 Year3 Year

Metrics Details

Article Description

The net initial passive flux (J(Ni)) in reconstituted plasma membrane (PM) vesicles from maize (Zea mays) root cells was measured as recently described (P. Pouliquin, J.-P. Grouzis, R. Gibrat [1999] Biophys J 76: 360-373). J(Ni) in control liposomes responded to membrane potential or to NO as expected from the Goldman-Hodgkin-Katz diffusion theory. J(Ni) in reconstituted PM vesicles exhibited an additional component (J(Nif)), which was saturable (K(m) for NO approximately 3 mM, with J(Nifmax) corresponding to 60 x 10 mol m s at the native PM level) and selective (NO = ClO > Br > Cl = NO; relative fluxes at 5 mM: 1:0.34:0.19). J(Nif) was totally inhibited by La and the arginine reagent phenylglyoxal. J(Nif) was voltage dependent, with an optimum voltage at 105 mV at pH 6.5. The activation energy of J(Nif) was high (129 kJ mol), close to that of the H-ATPase (155 kJ mol), and J(Nif) displayed the same acidic optimal pH (pH 6.5) as that of the H pump. This is the first example, to our knowledge, of a secondary transport at the plant PM with such a feature. Several properties of the NO uniport seem poorly compatible with that reported for plant anion channels and to be attributable instead to a classical carrier. The physiological relevance of these findings is suggested.

Bibliographic Details

Provide Feedback

Have ideas for a new metric? Would you like to see something else here?Let us know