Muscle glutamate transporter

Miller, C.L., Day, T.A., Bennett, J.L. and Rax, R.A. (1996) Schistosoma mansoni L glutamate-induced contractions in isolated muscle fibers evidence for a glutamate transporter. Experimental Parasitology 84, 410—41 9. 

The glucose-alanine cycle. Active muscle functions anaerobically and synthesizes alanine by a transamination reaction between glutamate and pyruvate, The alanine is transported to the liver, where the... 

Nitrogen is transported from muscle to the liver in two principal transport forms. Glutamate is formed by transamination reactions, but the nitrogen is then transferred to pyruvate to form alanine, which is released into the blood (Figure 23.15). 

Glutamate is transported to liver mitochondria, where glutamate dehydrogenase liberates the amino group as ammonium ion (NHJ). Ammonia formed in other tissues is transported to the liver as the amide nitrogen of glutamine or, in transport from skeletal muscle, as the amino group of alanine. 

The malate—aspartate shuttle is the mechanism by which electrons from NADH produced in the cytosol are transported into mitochondria, as the inner membrane is impermeable to NADH itself. Oxaloacetate is reduced to malate in the cytosol by malate dehydrogenase, in the process oxidizing NADH to replenish cytosolic NAD. The malate-aspartate shuttle is found mainly in cardiac muscle and liver cells, while the glycerol 3-phosphate shuttle operates mainly in brain and skeletal muscle cells. Once malate has entered the mitochondria it is oxidized to oxaloacetate, generating NADH within the mitochondrial matrix. Oxaloacetate is then converted to aspartate, which is transported out of the mitochondria in exchange for glutamate. 

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