Glutamate/glutamine shuttle

Figure 8.22 The glutamate/glutamine shuttle for provision of the glutamate neurotransmitter in the brain. This illustrates another role for glial cells in the brain.

Glutamate and glutamine metabolism is compartmentalized in brain 548 A specialized glutamate-glutamine cycle operates in GABAergic neurons and surrounding astrocytes 549 Several shuttles act to transfer nitrogen in brain 549... 

C14-0083. Although the ATP-ADP reaction is the principal energy shuttle in metabolic pathways, many other examples of coupled reactions exist. For example, the glutamic acid-glutamine reaction discussed in the text can couple with the acetyl phosphate reaction shown in Example 14-10. Write the balanced equation for the coupled reaction operating in the direction of overall spontaneity and calculate A G ° for the overall process. 

Interestingly, this lactate shuttling is not the only important metabolite exchange between these two cell types they also exchange glutamate and glutamine. Glutamate in small quantities is released at neuronal synapses as an... 

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