Biosynthesis of carcinoembryonic antigen (CEA) gene family members expressed in human tumor cell lines: evidence for cleavage of the glycosyl phosphatidyl inositol (GPI) anchor by GPI-PLC and GPI-PLD.
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, 70-100 kD; BGP, 85, 120 and 140 kD. Pulse chase experiments demonstrated that CEA first appears as a 165 kD high mannose precursor which is trimmed to a 160 kD intermediate and finally transformed into the mature 180 kD glycoprotein. The precursor form of NCA had a molecular weight of 50 kD. 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.
Khan
W N
WN
Dept of Immunology, University of Umeå, Sweden.
Hammarström
S
S
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D002272:Carcinoembryonic Antigen / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D015815:Cell Adhesion Molecules; D006023:Glycoproteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D008970:Molecular Weight; D005810:Multigene Family; D010716:Phosphatidylinositols / Q000737:chemistry; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000276:immunology
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C069847:CD66 antigens; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D010716:Phosphatidylinositols