Embryonal carcinomas and early embryonic cells assemble characteristic protein-linked glycans that have a very restricted distribution in the adult animal, and are lost in a programmed manner during early treatment. We have identified a carbohydrate-mediated adhesive system that is utilized by embryonal carcinomas. The carbohydrate determinant that is recognized is relatively unusual and is rapidly lost by embryonal carcinoma cells as they differentiate to endoderm. It is a branched, sulfated polylactosamine. Embryonal carcinoma glycosylation variants that are unable to express either branched polylactosamines or sulfated polylactosamines from loose colonies and are poorly adhesive in reaggregation assays. The branched, sulfated glycans, when immobilized on polystyrene, enhance teratocarcinoma attachment. Similar glycans that are either unbranched or unsulfated do not enhance attachment. The sulfated, branched polylactosamines do not enhance attachment of fibroblastic or endodermal cells. We will identify the smallest glycan determinant that is recognized by this sytem. We will prepare columns that carry immobilized glycans, either the branched, sulfated polylactosamines, or similar glycans that lack either the sulfation or the branching. We will then isolate teratocarcinoma proteins that are retained by columns containing the former glycans but not by columns containing the latter pair. We will isolate teratocarcioma variants that do not adhere to immobilized glycans, or do not adsorb fluorescent glycans using fluorescence activated cell sorting. We will charcterize their adhesive properties. (A)
