Autoantibodies to IA-2 in IDDM: location of major antigenic determinants.
Thirty-three IDDM sera that immunoprecipitated full-length IA-2 were tested for reactivity with different fragments of the IA-2 molecule. The fragments were prepared by PCR amplification of IA-2 cDNA and by expression in a rabbit reticulocyte transcription/translation system. Whereas all 33 sera reacted with the intracellular domain (amino acid 604 to 979), none of the sera reacted with the extracellular domain of IA-2 (amino acid 31 to 577). Analysis of the reactivity of IDDM sera with the different regions of the intracellular domain showed that 94% (31 of the 33) reacted with the COOH-terminus (amino acid 771 to 979), 40% reacted with the NH2-terminus (amino acid 604 to 776), and 40% reacted with the middle portion (amino acid 692 to 875). Of the 31 sera that reacted with the COOH-terminus, 14 of these reacted only with the COOH-terminus and with no other region. Of the 13 sera that reacted with the NH2-terminus, only one reacted exclusively with the NH2-terminus. Treatments of the different domains of IA-2 with trypsin showed that only the COOH-terminus was resistant to trypsin, arguing that it is from this region of the IA-2 molecule that the 40-kDa tryptic fragment from insulinoma cells is derived. From these experiments, it is concluded that the major antigenic determinant of IA-2 is located at the COOH-terminus and that minor antigenic determinants are located at the NH2-terminus and middle portion of the intracellular domain.
Zhang
B
B
Laboratory of Oral Medicine, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892-4322, USA.
Lan
M S
MS
Notkins
A L
AL
D000293:Adolescent; D000328:Adult; D000818:Animals; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D017931:DNA Primers; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008565:Membrane Proteins / Q000276:immunology*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology*; D011817:Rabbits; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D011994:Recombinant Proteins / Q000276:immunology
D001323:Autoantibodies; D001324:Autoantigens; D017931:DNA Primers; D008565:Membrane Proteins; D011994:Recombinant Proteins; C516862:PTPRN protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8