Biochemical characterization of the monoclonal antibody-defined ovarian carcinoma-associated antigen SGA.
The molecular nature of SGA, the ovarian-carcinoma-associated antigen defined by the MAb OM-1, has been determined. The cell-surface form of the SGA molecule is a glycoprotein with p1 less than 4.2, which on PAGE analysis has an apparent MW of approximately 360 kDa. This was the only OM-1-reactive species found on the cell surface. The apparent MW was unaffected by reducing conditions. The predominant cytoplasmic form of SGA is a non-glycosylated 170-kDa molecule with p1 6.5. Pulse-chase experiments were complicated by the extremely slow rate of SGA synthesis. However, the data indicate that the SGA molecule is synthesized as a 190-kDa protein, cleaved to yield a 170-kDa non-glycosylated intracellular form which is slowly glycosylated to the 360-kDa cell-surface species. Western blotting experiments revealed the presence of the 360-kDa glycosylated molecule in human ovarian cell culture supernatants.
T A
TA
de Kretser
H J
HJ
Thorne
D
D
Picone
D G
DG
Jose
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis; D002277:Carcinoma / Q000276:immunology*; D002460:Cell Line; D005110:Extracellular Space / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007526:Isoelectric Point; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000276:immunology; D010051:Ovarian Neoplasms / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D006023:Glycoproteins; D009363:Neoplasm Proteins; C017589:ovarian tumor associated antigen