A MONOCLONAL-ANTIBODY IDENTIFIES A NOVEL GPI-ANCHORED GLYCOPROTEIN INVOLVED IN EPITHELIAL INTERCELLULAR-ADHESION

BD31 mAb, raised against a line of gastric carcinoma cells, reacts wit h intercellular boundaries of human transformed cells originating from carcinomas or sarcomas growing in epithelial-like clusters as well as in primary cultures of epithelial and endothelial cells. BD31 also re acts with intercellular rims of normal and transformed epithelial tiss ues and is particularly abundant in glands and fast-growing epithelia but absent in nervous and muscle tissues as well as in blood and in me senchyme-derived cells. Confocal analysis indicates that BD31 is locat ed in dots at cell-cell contacts but not in basal and apical domains o f cultured and in situ epithelial cells. mAb BD31 precipitates a 100 k Da protein from cells labeled with [S-35]methionine or [H-3]glucosamin e as well as from I-125-surface-labeled cells. This glycoprotein resis ts to trypsin in the presence of Ca2+, releases an 80 kDa fragment in the medium and does not