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Cations stimulate proton pumping in Catharanthus roseus cells: implication of a redox system?
Author(s) -
BELKOURA M.,
RANJEVA R.,
MARIGO G.
Publication year - 1986
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1986.tb01623.x
Subject(s) - egta , divalent , chemistry , redox , biophysics , calmodulin , ion transporter , chelation , calcium , inorganic chemistry , catharanthus roseus , biochemistry , membrane , enzyme , biology , organic chemistry
During growth, cultured Catharanthus oseus cells produce a transient acidification of the culture medium that may be controlled by cations. The removal of divalent ions from the medium by the chelator EGTA resulted in an inhibition of this acidification. Conversely, acidification can be stimulated by the addition of Ca 2+ , Mg 2+ and La 3+ in the basal medium. This acidification process and the proton‐linked redox pump previously described (Marigo & Belkoura, 1985) respond in a similar manner to cations. These two systems, which are both inhibited by the Ca 2+ ‐calmodulin antagonist calmidazolium, could be regulated by the Ca 2+ ‐calmodulin complex. By using ionic surfactant (CP + , SDS − ) it was demonstrated that the net surface charge of the plasmalemma plays a role in the activation of the two pumping processes. These results are interpreted to indicate that a transmembrane redox system could provide the energy for electrogenic proton extrusion.