IDENTIFICATION OF A MAJOR POLY-N-ACETYLLACTOSAMINE-CONTAINING CELL-SURFACE GLYCOPROTEIN OF MOUSE TERATOCARCINOMA CELLS - APPEARANCE ON CELLS INDUCED TO PRIMITIVE ENDODERM BUT NOT PARIETAL ENDODERM DIFFERENTIATION

Mouse teratocarcinoma F9 cells were induced to primitive endoderm diff erentiation with retinoic acid, and poly-N-acetyllactosamine-containin g surface glycoproteins were identified by radiolabelling endo-beta-ga lactosidase-cleavable glycans with galactosyltransferase and radiolabe lled UDP-galactose. One major radiolabelled band with an apparent size of 250-500 kDa was identified which differed from the known poly-N-ac etyllactosamine-containing glycoproteins laminin, fibronectin, lysosom e-associated membrane protein (LAMP)-1 and LAMP-2. This acidic glycopr otein, resistant to glycosaminoglycan-degrading enzymes and proteases, was purified by extraction and phase partition with Triton X-114, oct yl Sepharose and Helix pomatia lectin chromatography. The purified gly coprotein could be digested by endo-beta-galactosidase and glycopeptid e N-glycosidase F to an apparent size of 160-240 kDa. During retinoic- acid-induced differentiation into primitive endoderm cells, the glycop rotein showed a several-fold increase and a broadening to an apparent size of 200 - > 700 kDa. The glycoprotein was no longer detected in re tinoic-acid and dibutyryl-cAMP-treated cells which had undergone furth er differentiation to parietal endoderm cells, nor in the permanently differentiated parietal endoderm line F9-AC. The results suggest that the glycoprotein is a major carrier of poly-N-acetyllactosamine chains on differentiating teratocarcinoma F9 cells, and that its expression as revealed by the poly-N-acetyllactosamine labelling method is regula ted by the stage of cellular differentiation.