An epitope on Ki antigen recognized by autoantibodies from lupus patients shows homology with the SV40 large T antigen nuclear localization signal.
OBJECTIVE
Epitopes on Ki antigen were analyzed using synthetic peptides, including KILT, a 16-mer peptide with an amino acid sequence homologous to the SV40 large T antigen nuclear localization signal (SV40 T NLS).


METHODS
In addition to KILT, 4 synthetic peptides, all potential epitopes on Ki antigen according to computer analysis, were prepared and tested for reactivity with 49 anti-Ki-positive lupus sera by enzyme-linked immunosorbent assay.


RESULTS
Eighteen sera reacted with KILT, but not with other peptides. The reaction of anit-Ki sera with KILT was specifically inhibited by recombinant Ki antigen. Eight of 49 anti-Ki sera reacted with a 7-mer synthetic peptide of SV40 T NLS, and the reaction was specifically inhibited by KILT.


CONCLUSIONS
The 16-mer Ki peptide containing the sequence homologous to the SV40 T NLS is one of the antigenic epitopes recognized by anti-Ki antibodies in lupus sera.
Takasaki
Y
Y
Juntendo University School of Medicine, Tokyo, Japan.
Yano
T
T
Hirokawa
K
K
Takeuchi
K
K
Ando
S
S
Takahashi
T
T
Shimada
K
K
Hashimoto
H
H
D000595:Amino Acid Sequence; D000918:Antibody Specificity; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens; D002467:Cell Nucleus / Q000276:immunology*; D000939:Epitopes; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000276:immunology*; D009842:Oligopeptides / Q000276:immunology; D010455:Peptides / Q000276:immunology; D046988:Proteasome Endopeptidase Complex; D011994:Recombinant Proteins / Q000276:immunology; D017386:Sequence Homology, Amino Acid
D000952:Antigens, Polyomavirus Transforming; D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; C099559:KILT protein, synthetic; C099558:Ki antigen; C099560:LTSP protein, synthetic; D009687:Nuclear Proteins; D009842:Oligopeptides; D010455:Peptides; D011994:Recombinant Proteins; D046988:Proteasome Endopeptidase Complex