Three Carcinoembryonic Antigen (CEA) gene family members: CEA, Non-specific cross-reactive antigen 50/90 (NCA) and biliary glycoprotein (BGP) were expressed in the colon carcinoma cell lines LS174T and HT29. The CEA, NCA50/90 and four alternatively spliced BGP transcripts (BGP a-d) were identified. The molecular weights of the mature glycoproteins were: CEA, 180kD; NCA50/90, 70-100kD; BGP, 85, 120 and 140kD. Pulse chase experiments demonstrated that CEA first appears as a 165kD high mannose precursor which is trimmed to a 160kD intermediate and finally transformed into the mature 180kD glycoprotein. The precursor form of NCA had a molecular weight of 50kD. CEA and NCA50/90, but not BGP, were linked to the cell membrane via glycosyl phosphatidyl inositol and could be released from the intact tumor cells by glycosyl phosphatidyl inositol-specific phospholipase C. CEA on isolated membranes and in cell lysates, but not on intact cells, was also cleaved by fresh human serum or purified glycosyl phosphatidyl inositol-specific phospholipase D.
|Original language||English (US)|
|Number of pages||9|
|State||Published - Dec 1 1991|
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