Identification and role of plasma membrane aquaporin in maize root

Using antiserum against expressed aquaporin fusion protein, GST-RD28, the d istribution of aquaporin in the plasma membrane of maize root protoplasts h as been examined under confocal laser scanning microscopy by indirect fluor escence staining. Results indicate that there are abundant aquaporins in ma ize roots, which are distributed in plasma membrane unevenly. Western blott ing analysis of total protein solubilized from maize root plasma membrane s hows that antiserum against GST-RD28 can cross-react with one protein aroun d 55 ku. Another 28 ku protein can also be detected when the concentration of SDS and DTT in SDS-PAGE sample buffer is increased. The 55 and 28 ku pro teins may be dimeric and monomeric of aquaporin respectively. Functional ex periments show that aquaporin blocker HgCl2 and aquaporin antiserum can sup press the swelling of maize root protoplasts in hypotonic solution, indicat ing that aquaporin in plasma membrane of protoplast facilitates rapid trans membrane water flow.