Identification of Lewis x structures of the cell adhesion molecule CEACAM1 from human granulocytes

Carcinoembryonic antigen–related cell adhesion molecule 1 (CEACAM1) is expressed on epithelia, blood vessel endothe-lia, and leukocytes. A variety of physiological functions have been assigned to CEACAM1. It is involved in the formation of glands and blood vessels, in immune reactions, and in the regulation of tumor growth. As a homophilic and heterophilic adhesion receptor, it signals through different cellular path-ways. The existence of special oligosaccharide structures such as Lewis x or sialyl-Lewis x glycans within this highly glyco-sylated protein has been postulated, but chemical proof is missing so far. Because such structures are known to be essential for different cell–cell recognition and adhesion pro-cesses, characterizing the CEACAM1 glycan structure is of pivotal importance in revealing the biological function of CEACAM1. We examine the terminal glycosylation patter