DOI Page / Citation link:
https://doi.org/10.11588/diglit.48120#0033
Abstracts
15
12. Bruder, G., Jarasch, E.-D., Heid, H.W. (1984): High concentrations of antibodies
to Xanthine oxidase in human and animal sera. J. Clin. Invest. 74, 783-794
13. Cohen, I.R., Cooke, A. (1986): Natural autoantibodies might prevent autoimmunue
disease. Immunol. Today 7, 363-364
14. Hansson, G.K., Lagerstedt, E., Bengtsson, A., Heideman, M. (1987): IgB bind-
ing to cytoskeletal intermediate filaments activates the complement cascade. Exp. Cell
Res. 170, 338-350
Leucine Periodicity of U2 snRNP Autoantigen A'
Implicated in U2 snRNP Protein: Protein Interactions
L.D. Fresco and J. D. Keene
Department of Microbiology and Immunology, Duke University Medical Center Durham,
North Carolina, USA
A’ is unique protein component of the U2 class of U snRNPs that mediate
splicing in metazoan nuclei. Moreover, it is an autoantigen recognized by a rare
subset of autoimmune sera directed against unique epitopes of the U2 snRNP.
Anti-(U2) RNP autoantibodies, reactive with U2 RNP-specific proteins A' and
B", occur in patients with rheumatic overlap syndromes that include myositis as
a common feature.
To gain further insight into the structure of the U2 snRNP and to facilitate
analysis of the structural basis of its function, the cDNA and gene encoding
human A' were cloned and analyzed using a (U1/U2) RNP human autoantiserum
as the initial probe. Analysis of A' mRNA and a corresponding genomic clone
demonstrated that the A' gene, spanning almost 20 Kb, encompasses nine exons.
A putative regulatory region that is reminiscent of many constitutively expressed
“housekeeping” genes resides upstream of the transcription start site. The prima-
ry structures of various cDNA clones recovered from libraries of different tissues
suggest that two different isoforms arise by alternative splicing of the primary A'
mRNA. Sequence analysis of a full-length cDNA disclosed an ORF that encodes
a 225 amino acid protein of 28,419 Da.
To explore the role of snRNP proteins in splicing and to study snRNP
assembly, we have initially reconstituted the U2 snRNP complex using wild type
and mutant forms of A'. Upon incubation in a HeLa cell nuclear extract, in vitro
synthesized A' was able to assemble into a U2 snRNP, either by exchange or by
de novo assembly, as defined by particle density and coimmunoprecipitation. To
delineate the limits of the A' polypeptide required for this reconstitution, associa-
15
12. Bruder, G., Jarasch, E.-D., Heid, H.W. (1984): High concentrations of antibodies
to Xanthine oxidase in human and animal sera. J. Clin. Invest. 74, 783-794
13. Cohen, I.R., Cooke, A. (1986): Natural autoantibodies might prevent autoimmunue
disease. Immunol. Today 7, 363-364
14. Hansson, G.K., Lagerstedt, E., Bengtsson, A., Heideman, M. (1987): IgB bind-
ing to cytoskeletal intermediate filaments activates the complement cascade. Exp. Cell
Res. 170, 338-350
Leucine Periodicity of U2 snRNP Autoantigen A'
Implicated in U2 snRNP Protein: Protein Interactions
L.D. Fresco and J. D. Keene
Department of Microbiology and Immunology, Duke University Medical Center Durham,
North Carolina, USA
A’ is unique protein component of the U2 class of U snRNPs that mediate
splicing in metazoan nuclei. Moreover, it is an autoantigen recognized by a rare
subset of autoimmune sera directed against unique epitopes of the U2 snRNP.
Anti-(U2) RNP autoantibodies, reactive with U2 RNP-specific proteins A' and
B", occur in patients with rheumatic overlap syndromes that include myositis as
a common feature.
To gain further insight into the structure of the U2 snRNP and to facilitate
analysis of the structural basis of its function, the cDNA and gene encoding
human A' were cloned and analyzed using a (U1/U2) RNP human autoantiserum
as the initial probe. Analysis of A' mRNA and a corresponding genomic clone
demonstrated that the A' gene, spanning almost 20 Kb, encompasses nine exons.
A putative regulatory region that is reminiscent of many constitutively expressed
“housekeeping” genes resides upstream of the transcription start site. The prima-
ry structures of various cDNA clones recovered from libraries of different tissues
suggest that two different isoforms arise by alternative splicing of the primary A'
mRNA. Sequence analysis of a full-length cDNA disclosed an ORF that encodes
a 225 amino acid protein of 28,419 Da.
To explore the role of snRNP proteins in splicing and to study snRNP
assembly, we have initially reconstituted the U2 snRNP complex using wild type
and mutant forms of A'. Upon incubation in a HeLa cell nuclear extract, in vitro
synthesized A' was able to assemble into a U2 snRNP, either by exchange or by
de novo assembly, as defined by particle density and coimmunoprecipitation. To
delineate the limits of the A' polypeptide required for this reconstitution, associa-