Characteristics of Ammonium Transport System

The following are the characteristics of ammonium transport system:

1. Ammonium transport system is ammonia' repressible as it is absent in cultures grown with ammonia as 'nitrogen source;
2. Nitrogen limitation for growth appears to be the signal for the induction of the Ammonium transport system
3. Ammonium transport system like other transport processes is an energy requiring active process.

Since higher levels of ammonia in lower plant cells like cyanobacteria exert toxic effects, there must occur a closer interrelationship between uptake and assimilation of ammonia in such systems. Further studies are required to clearly understand the interdependence of the two processes. At this point it is important to point out that the characteristics of ammonium transport process has not been studied in higher plants.