Passive anion transport through the chloroplast inner envelope membrane measured by osmotic swelling of intact chloroplasts.

It has been shown that chloride channels are located in the envelope membranes of chloroplasts [5,11]. In this report, we use the light-scattering technique to measure quantitatively the rate of anion transport through the inner envelope membrane of isolated intact chloroplasts. Our results permit to assign the anion transport to the inner envelope of chloroplasts. The anionic selectivity determined from the kinetics of light scattering indicates that the chloride pathway is also highly permeable for NO-2 and NO-3. The sulfate and phosphate anions are impermeant. The chloride flux is not inhibited by DIDS or NEM and is temperature-dependent. The activation energy of the transport process suggests that the Cl- flux occurs through a channel.