DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0119
Abstracts
101
tive serum drawn from a patient who subsequently became AJoA positive. No
hexapeptides reacted solely with AJoA positive sera, indicating that no linear
epitopes of this molecule are recognized by AJoA.
In order to characterize further the target or the antibodies, we examined the
ability of AJoA to inhibit the function of HRS from various species. Other
studies had shown that the bovine as well as human but not the E. coli enzyme
are bound and inhibited by AJoA. AJoA inhibited the aminoacylation of
histidine to its respective tRNA in human, anole, frog, and fish cytoplasmic ex-
tracts by 90.0%, 89.1 %, 82.5%, and 52.2% respectively. No inhibition of HRS en-
zyme activity was observed for yeast, euglena, amoeba, algae, or E. coli extracts.
These data suggest that these autoantibodies recognize a conformational, not
a linear, epitope of HRS, critical to enzyme function, conserved throughout the
animal kingdom, but not present in the other four kingdoms. The ability of AJoA
to inhibit HRS activity through phylogeny suggests that the autoantibodies
recognize a relatively conserved region of the antigen. The preferential inhibition
of human HRS and the decreasing inhibition as phylogenetic distance from man
increases suggest that the human enzyme may have a critical role in this antibody
response.
Molecular Considerations of Primary Biliary Cirrhosis: Definition of
Dihydrolipoamide Acetyltransferase and Identification of
Immunoreactive Sites
J. Van de Water, P. Leung, A. Ansari, R.L. Coppel, and M.E. Gershwin
Div. Rheumatology-Clinical Immunology, University of California, Davis, California;
Dept. Pathology, Emory University, Atlanta, GA; Hall Institute, Melbourne, Australia
Autoantibodies to mitochondrial antigens are characteristic of primary biliary
cirrhosis, but the precise antigenic determinants recognized by these antibodies
have not ben defined. We have identified and sequenced both human and rat
genes that code for a polypeptide recognized specifically by sera from patients
with PBC but not by sera from patients with other forms of liver disease. This
recombinant protein was identified as the 74 kD M2 mitochondrial inner mem-
brane autoantigen, dihydrolipoamide acetyltransferase. We have identified a
603 bp fragment (pRMIT-603) which codes for a polypeptide containing all of the
autoreactivity of the original clone. Based on hydrophobicity/hydrophilicity plots
101
tive serum drawn from a patient who subsequently became AJoA positive. No
hexapeptides reacted solely with AJoA positive sera, indicating that no linear
epitopes of this molecule are recognized by AJoA.
In order to characterize further the target or the antibodies, we examined the
ability of AJoA to inhibit the function of HRS from various species. Other
studies had shown that the bovine as well as human but not the E. coli enzyme
are bound and inhibited by AJoA. AJoA inhibited the aminoacylation of
histidine to its respective tRNA in human, anole, frog, and fish cytoplasmic ex-
tracts by 90.0%, 89.1 %, 82.5%, and 52.2% respectively. No inhibition of HRS en-
zyme activity was observed for yeast, euglena, amoeba, algae, or E. coli extracts.
These data suggest that these autoantibodies recognize a conformational, not
a linear, epitope of HRS, critical to enzyme function, conserved throughout the
animal kingdom, but not present in the other four kingdoms. The ability of AJoA
to inhibit HRS activity through phylogeny suggests that the autoantibodies
recognize a relatively conserved region of the antigen. The preferential inhibition
of human HRS and the decreasing inhibition as phylogenetic distance from man
increases suggest that the human enzyme may have a critical role in this antibody
response.
Molecular Considerations of Primary Biliary Cirrhosis: Definition of
Dihydrolipoamide Acetyltransferase and Identification of
Immunoreactive Sites
J. Van de Water, P. Leung, A. Ansari, R.L. Coppel, and M.E. Gershwin
Div. Rheumatology-Clinical Immunology, University of California, Davis, California;
Dept. Pathology, Emory University, Atlanta, GA; Hall Institute, Melbourne, Australia
Autoantibodies to mitochondrial antigens are characteristic of primary biliary
cirrhosis, but the precise antigenic determinants recognized by these antibodies
have not ben defined. We have identified and sequenced both human and rat
genes that code for a polypeptide recognized specifically by sera from patients
with PBC but not by sera from patients with other forms of liver disease. This
recombinant protein was identified as the 74 kD M2 mitochondrial inner mem-
brane autoantigen, dihydrolipoamide acetyltransferase. We have identified a
603 bp fragment (pRMIT-603) which codes for a polypeptide containing all of the
autoreactivity of the original clone. Based on hydrophobicity/hydrophilicity plots