A 41 KDA PROTEIN ISOLATED FROM MAIZE MESOCOTYL CELL-WALLS IMMUNOLOCALIZES TO PLASMODESMATA

Plasmodesmata, dynamic pore structures that traverse plant cell walls, function in cytoplasmic transport between contiguous cells. Cell wall s containing embedded plasmodesmata were isolated from mesocotyls of e tiolated maize seedlings. Proteins associated with the isolated walls were separated by SDS-PAGE and antibodies were generated against a 41 kDa protein, one of several associated with this wall fraction. Immuno blot analysis showed that the 41 kDa polypeptide was also associated w ith other subcellular fractions obtained following tissue homogenizati on and differential centrifugation. The wall associated 41 kDa protein is apparently a peripheral membrane protein since it could be extract ed by high salt and high pH. Silver-enhanced immunogold light microsco py showed that the 41 kDa protein was associated with the cell walls o f cells both in the stele and cortex. The immunolabeling pattern was t rans-wall and punctate. Electron microscopic immune-gold labeling loca lized the polypeptide to plasmodesmata and to electron dense cytoplasm ic structures that are apparently Golgi membranes. The significance of the presence of this protein in the Golgi is discussed.