Glutamine synthetase isoforms

Fig. 1. The nitrate assimilation pathway in higher plants. The pathway of nitrate assimilation in the tobacco leaf is illustrated. In some other species an additional cytosolic GS is found in the leaf. The pathway in plant roots is more poorly documented and more variable GS in roots is mostly cytosolic, and some enzymes such as GOGAT are found as isoforms utilising alternate reducing substrates. T, expected nitrate carrier NR, nitrate reductase NiR, nitrite reductase GS, glutamine synthetase GOGAT, glutamate synthase Fd, ferredoxin Gin, glutamine Glu, glutamate.

There is evidence to suggest that oxidative and nitrosative stress play a role in the pathogenesis of HE. Induction of NOS isoforms have been desalbed in the brain in liver failure and the consequent nitration of key brain proteins such as glutamine synthetase has been reported. 

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