N-GLYCANS HARBORING THE LEWIS A EPITOPE ARE EXPRESSED AT THE SURFACE OF PLANT-CELLS

In plants, N-linked glycans are processed in the Golgi apparatus to co mplex-type N-glycans of limited size containing a beta(1,2)-xylose and /or an alpha(1,3)-fucose residue. Larger mono-and bi-antennary N-linke d complex glycans have not often been described. This study has re-exa mined the structure of such plant N-linked glycans, and, through both immunological and structural data, it is shown that the antennae are c omposed of Lewis a (Le(a)) antigens, comprising the carbohydrate seque nce Gal beta 1-3[Fuc alpha 1-4]GlcNAc. Furthermore, a fucosyltransfera se activity involved in the biosynthesis of this antigen was detected in sycamore cells. This is the first characterization in plants of a L ewis antigen that is usually found on cell-surface glycoconjugates in mammals and involved in recognition and adhesion processes. Le(a)-cont aining N-linked glycans are widely distributed in plants and highly ex pressed at the cell surface, which may suggest a putative function in cell/cell communication.