Astrocytes are also thought to have high-affinity uptake systems for neurotransmitters such as glutamate and gamma-aminobutyric acid (GABA).
Both glutamate and aspartate are probably inactivated by uptake systems at the presynaptic terminals and at glial cells surrounding some of the synaptic junctions.
Uptake systems tend to terminate neurotransmitter action at the synapses and may also act as storage systems for neurotransmitters when they are needed.
We also tested RB specificity in other neurotransmitter uptake systems.
Streptomycetes can further promote mineral supply by synthesizing siderophores and siderophore uptake systems [107].
Yeast cells acquire iron at the plasma membrane by utilizing high- and low-affinity iron uptake systems (Fig. 1).
Using different substrates as limiting and pulse-substrates (glucose, glycerol), different metabolic pathways and substrate uptake systems are investigated.
The Trojan horse concept involves the use of bacterial iron uptake systems to enter and kill bacteria.
The neisserial iron uptake systems are summarized in Figure 1.
S. typhimurium seems to possess all three known potassium uptake systems (TrK, Kdp and Kup).
The yeast strain 22Δ8AA, which lacked eight endogenous amino acid uptake systems [7], was used.
