High resolution 2-D electrophoresis of polypeptides of maize root plasma membrane : Identification of polypeptides whose expression is regulated by nitrate

The nitrate-dependent changes in the polypeptide pattern of maize (Zea mays L.) root plasma membrane have been analysed using two-dimensional gel electrophoresis and [ 35 S] methionine labelling. An optimized 2-D PAGE technique was used and gave reproducible 2-D gels from plasma membrane proteins with a high number of detected polypeptides and very low streaking. Moreover, the variability inherent to the technique was taken into account to discard artifactual results. Two plasma membrane polypeptides of 61 and 39 kDa displayed an increased [ 35 S] labelling following nitrate induction. These polypeptides might be related to a root membrane nitrate carrier.