Structure
The transmembrane respiratory nitrate reductase (EC) is composed of three subunits; an alpha, a beta and two gamma. It is the second nitrate reductase enzyme which it can substitute for the NRA enzyme in Escherichia coli allowing it to use nitrate as an electron acceptor during anaerobic respiration.
Nitrate reductase gamma subunit resembles cytochrome b and transfers electrons from quinones to the beta subunit.
The nitrate reductase of higher plants is a cytosolic protein. There exists a GPI-anchored variant that is found on the outer face of the plasma membrane. It's exact function is still not clear.
A transmembrane nitrate reductase that can function as a proton pump (similar to the case of anaerobic respiration) has been discovered in a diatom Thalassiosira weissflogii.
Read more about this topic: Nitrate Reductase
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