THE WAXY (WX) PROTEINS OF MAIZE, RICE AND BARLEY

Maize waxy (Wx) protein, which has been detected as a single protein with a M(r) 60000 by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), was separated into four isoforms by 2D-PAGE. The isoelectric point (pI) of these isoforms ranged from 6.0 to 6.5. Starch isolation with SDS-buffer and heat-extraction of protein from starch granules had no effect on the 2D electrophoretic patterns of Wx protein. Rice and barley Wx proteins were also analysed by the same method and separated into four and three isoforms, respectively. Rice Wx protein isoforms had a M(r) of 60000 as had been reported with a pI range from 6.5 to 7.2 while barley Wx protein isoforms had a M(r) of 61 000 and pI in the range of 5.8 to 6.3.