Expression of NAD glycohydrolase activity by rat mammary adenocarcinoma cells transformed with rat T cell alloantigen RT6.2.
RT6.2 is a 26-kDa alloantigen expressed only on post-thymic T cells and attached to the cell membrane through a glycosylphosphatidylinositol (GPI) anchor. It has been reported that expression of RT6.2 in animal models may correlate with lymphopenia and genetically-induced insulin-dependent diabetes mellitus. Its physiological function is unclear. Since RT6.2 has significant amino acid identity with a GPI-anchored rabbit muscle NAD:arginine ADP-ribosyltransferase, RT6.2 was expressed in rat mammary adenocarcinoma cells and the ability of the expressed protein to catalyze ADP-ribose transfer reactions was examined. Cells transformed with the RT6.2 gene expressed NAD glycohydrolase activity that was released from intact cells by phosphatidylinositol-specific phospholipase C, consistent with its presence on the cell surface. A similar activity was not detected with vector-transformed cells. RT6.2 did not ADP-ribosylate simple guanidino compounds. The molecular weight of the phosphatidylinositol-specific phospholipase C-released NAD glycohydrolase, determined by SDS-polyacrylamide gel electrophoresis, was 22,000-24,000, in good agreement with that of native RT6.2. These results strongly suggest that the rat T cell alloantigen RT6.2 is a GPI-anchored NAD glycohydrolase.
Takada
T
T
Laboratory of Cellular Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Iida
K
K
Moss
J
J
D036002:ADP Ribose Transferases; D000230:Adenocarcinoma / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D001483:Base Sequence; D002461:Cell Line, Transformed; D017931:DNA Primers; D006649:Histocompatibility Antigens / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology*; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology; D009244:NAD+ Nucleosidase / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics; D011817:Rabbits; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014407:Tumor Cells, Cultured
D000945:Antigens, Differentiation, T-Lymphocyte; D017931:DNA Primers; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; C090163:Art2b protein, rat; D009244:NAD+ Nucleosidase