OLIGOMERIZATION OF N-TERMINAL DOMAIN OF CARCINOEMBRYONIC ANTIGEN (CEA) EXPRESSED IN ESCHERICHIA-COLI

The N-terminal domain of CEA, which is essential for cell adhesion act ivity and lacks cysteine residue, was expressed in Escherichia coli an d purified from the solubilized inclusion bodies by DEAE-Sepharose and gel filtration chromatographies. The purified N-domain migrated in SD S-PAGE as a single 13-kDa band, whereas it migrated in non-SDS-PAGE as five distinct bands. The N-domain, analyzed by two-dimensional PAGE a fter cross-linking with DSS, migrated in multiple forms ranging from m onomer to pentamer, showing unequivocally the presence of multimers in each band. The amount of monomer was distinctively the least among th e oligomers in the non-SDS-PAGE. These results suggest that the N-doma in of CEA molecule has a strong tendency to self-assemble that may con vey the hemophilic cell adhesion of CEA. (C) 1998 Academic Press.