Expression in BALB/c and C57BL/6 mice of Rt6-1 and Rt6-2 ADP-ribosyltransferases that differ in enzymatic activity: C57BL/6 Rt6-1 is a natural transferase knockout.
Several proteins with NAD+:arginine ADP-ribosyltransferase (ART) activity are expressed in T cells and affect their function. Rat T cells that express the ART designated RT6 are determinants of the expression of autoimmune diabetes. In the mouse, a 35-kDa ecto-ART modulates the proliferation and functional activity of CTL. Here we report on mouse ARTs designated Rt6-1 and Rt6-2 in BALB/c and C57BL/6 mice. mRNAs for Rt6-1 and Rt6-2 were found in spleen, thymus, and intestinal tissue of both strains, but Rt6-1 mRNA in C57BL/6 mice was detected only at low levels. Rt6-1 and Rt6-2 cDNAs from both strains were cloned and sequenced. Predicted amino acid sequences of Rt6-2 were identical in both strains, but there was an in-frame stop codon in the sequence of Rt6-1 in C57BL/6 mice not present in BALB/c mice. Recombinant C57BL/6 Rt6-2 and BALB/c Rt6-1 proteins expressed in COS1 cells exhibited ART activity and were documented to be glycosylphosphatidylinositol-linked membrane proteins. COS-1 cells transfected with a C57BL/6 Rt6-1 cDNA construct expressed a truncated protein consistent in size with that predicted by the presence of the stop codon. This approximately 21-kDa protein appeared not to be glycosylphosphatidylinositol linked to the cell surface and lacked ART activity. C57BL/6 Rt6-1 therefore appears to be a naturally occurring ART knockout. The expression of Rt6-1 and Rt6-2 mRNAs in lymphoid tissues suggests that these ARTs may regulate immune system functions. Expression of Rt6-2 or another redundant ART may compensate for the lack of enzymatically active Rt6-1 in C57BL/6 mice.
Kanaitsuka
T
T
Department of Medicine, University of Massachusetts Medical Center, Worcester 01655, USA.
Bortell
R
R
Stevens
L A
LA
Moss
J
J
Sardinha
D
D
Rajan
T V
TV
Zipris
D
D
Mordes
J P
JP
Greiner
D L
DL
Rossini
A A
AA
D036002:ADP Ribose Transferases; D000595:Amino Acid Sequence; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D002851:Chromatography, High Pressure Liquid; D006649:Histocompatibility Antigens / Q000096:biosynthesis / Q000235:genetics*; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D011065:Poly(ADP-ribose) Polymerases / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D016415:Sequence Alignment; D013045:Species Specificity
D000945:Antigens, Differentiation, T-Lymphocyte; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; C449322:Art2a protein, mouse; C449339:Art2b protein, mouse; C090163:Art2b protein, rat