Botany online 1996-2004. No further update, only historical document of botanical science!
The hypothetical model of a plasma membrane vesicle. S = specific auxin-proton carrier (symport), AC = specific auxin-anion carrier (active antiport). The driving force of the IAA flow through the membrane is a proton gradient (according to R. HERTEL et al., 1983).
Vesicles of Curcubita hypocotyl or Zea mays containing auxin carriers can be dismantled into smaller vesicles (on the left and on the right of the illustration). After centrifugation in a dextran-sucrose gradient is a vesicle fraction obtained that has just one type of auxin carrier (S, blue). Its effect is not influenced by a specific inhibitor. On the other hand is a fraction gained that contains both types of auxin carriers (red and blue). The activity of one of them can be influenced by an inhibitor (R. HERTEL, 1988).