Glutamate translocator

Grewer, C., Watzke, N., Wiessner, M., and Rauen, T. (2000) Glutamate translocation of the neuronal glutamate transporter EAAC1 occurs within milliseconds Proc. Natl. Acad. Sci. USA 97, 9706-9711. 

At equilibrium of the citrate-malate exchange system log[(citrate/ malate), /(citrate/malate), ] = ApH, since one H" " accompanies citrate in its exchange for malate. This value must be equal to the logarithm of the pyruvate and glutamate concentration gradients if both the pyruvate and glutamate translocators are also at equilibrium. 

Synaptic vesicles isolated from brain exhibit four distinct vesicular neurotransmitter transport activities one for monoamines, a second for acetylcholine, a third for the inhibitory neurotransmitters GABA and glycine, and a fourth for glutamate [1], Unlike Na+-dependent plasma membrane transporters, the vesicular activities couple to a proton electrochemical gradient (A. lh+) across the vesicle membrane generated by the vacuolar H+-ATPase ( vacuolar type proton translocating ATPase). Although all of the vesicular transport systems rely on ApH+, the relative dependence on the chemical and electrical components varies (Fig. 1). The... 

Seal, R. P. and Amara, S. G. (1998) A reentrant loop domain in the glutamate carrier EAAT1 participates in substrate binding and translocation. Neuron 21,1487-1498. 

Blocker, D., Bachmeyer, C., Benz, R., Aktories, K. and Barth, H., Channel formation by the binding component of Clostridium botulinum C2 toxin glutamate 307 of C2II affects channel properties in vitro and pH-dependent C2I translocation in vivo, Biochem., 42, 5368-5377, 2003. 

The interconversion of o -ketoglutarate to glutamate involves the malate-aspartate shutde. This shuttle translocates a-ketoglutarate from mitochondria into the cytoplasm and then converts it to glutamate by the catalytic action of aspartate aminotransferase (McKenna et al., 2006). As part of the malate-aspartate shuttle, NADH is oxidized during reduction of oxaloacetate to malate. Malate diffuses across the outer mitochondrial membrane (Fig. 1.6). From the intermembrane space, the malate-a-ketoglutarate antiporter in the inner membrane transports malate into the matrix. For every malate molecule entering the matrix compartment, one molecule of... 

Vaccarino F., Guidotti A., and Costa E. (1987). Ganglioside inhibition of glutamate-mediated protein kinase C translocation in primary cultures of cerebellar neurons. Proc. Natl. Acad. Sci. USA 84 8707-8711. 

A direct K+ requirement for translocation has, however, been reported for glutamic acid transport in brain (Kanner and Schuldiner, 1987 Carlson et al., 1989). The dicarboxylic amino acids appear to be transported largely by specific transporters which do not participate in neutral amino acid transport. Recent studies, both in reconstituted systems and the expression of the cloned transporter, have confirmed the K+ requirement (see below). 

The compound dicyclohexylcarbodiimide (DCCD) inhibits proton translocation through F0 by reacting with the carboxyl group of a single glutamate residue in the channel-forming loop of the proteolipid. 

Backgren, C., Hummer, G., Wiksstroem, M, and Puustinen, A. (2000) Proton translocation by cytochrome c oxidase can take place without conserved glutamic acid in subunit I., Biochemistry, 39, 7863-7867. 

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