DOI Page / Citation link:
https://doi.org/10.11588/diglit.48120#0034
16 Molecular and Cell Biology of Autoantibodies and Autoimmunity
tion of N-terminal and C-terminal deletion mutants of A' was examined. The re-
quired region encompassed a portion of the molecule that displays significant in-
ternal homology. This segment comprises at least five approximately 24 amino
acid tandem repeats that exhibit a periodicity of leucine and asparagine residues.
This repeated motif, distinct from the “leucine zipper”, is conserved in a wide ar-
ray of proteins with diverse biological roles whose common feature is a role in
protein: protein interactions: mammalian RNase/angiogenin inhibitors; the
subunits of the human platelet integral plasma membrane heterodimer, F Gib; the
proteoglycan core proteins of human placenta fibroblasts, PG40, and bovine
bone, PG-II; Drosophila Toll gene product that specifies dorsal-ventral polarity
of the early embryo; Drosophila chaoptin, a cell surface glycoprotein; and yeast
adenylate cyclase. Occurrence of this motif in species from yeast to human implies
that this element defines a widely utilized structural motif that presumably func-
tions in protein: protein interactions. Unique regions of A' feature sequence
similarity to the 50S ribosomal protein LI of E. coli and a highly acidic
hydrophilic C-terminal tail, which appear to be non-essential for association with
the U2 snRNP. Autoantigenic epitopes reside in both N-terminal and C-terminal
regions of the molecule. A' provides the first example of a nuclear protein that
possesses a leucine-rich amphipathic repeat motif, and the requirement of this
region for association with the U2 snRNP is compatible with a role in prote-
in : protein interactions. Currently, we are testing the proposal that the repeated
motify mediates specific protein: protein interactions of the U2 snRNP wihtin the
spliceosome.
Epitope Mapping of the Recombinant Human UlsnRNP 68 k Protein
H. Fujii1, K. Yamamoto1, H. Kohsaka1, Y. Tanaka’, H. Miura1, Y. Misaki1,
K. Nishioka2, and T. Miyamoto1
1 Department of Medicine and Physical Therapy, Faculty of Medicine,
University of Tokyo, Japan
2 Institute of Rheumatology, Tokyo Women’s Medical College, Tokyo, Japan
UlsnRNP 68 k protein is a major target molecule of anti-RNP antibodies
found in mixed connective tissue disease and other autoimmune diseases. In order
to investigate the mechanisms of autoantibody production and pathogenesis, we
have screened two different human cDNA libraries (fibroblast and fore skin) us-
ing a cDNA clone FL70K (kindly supplied by Drs. Luhrmann and Philipson).
tion of N-terminal and C-terminal deletion mutants of A' was examined. The re-
quired region encompassed a portion of the molecule that displays significant in-
ternal homology. This segment comprises at least five approximately 24 amino
acid tandem repeats that exhibit a periodicity of leucine and asparagine residues.
This repeated motif, distinct from the “leucine zipper”, is conserved in a wide ar-
ray of proteins with diverse biological roles whose common feature is a role in
protein: protein interactions: mammalian RNase/angiogenin inhibitors; the
subunits of the human platelet integral plasma membrane heterodimer, F Gib; the
proteoglycan core proteins of human placenta fibroblasts, PG40, and bovine
bone, PG-II; Drosophila Toll gene product that specifies dorsal-ventral polarity
of the early embryo; Drosophila chaoptin, a cell surface glycoprotein; and yeast
adenylate cyclase. Occurrence of this motif in species from yeast to human implies
that this element defines a widely utilized structural motif that presumably func-
tions in protein: protein interactions. Unique regions of A' feature sequence
similarity to the 50S ribosomal protein LI of E. coli and a highly acidic
hydrophilic C-terminal tail, which appear to be non-essential for association with
the U2 snRNP. Autoantigenic epitopes reside in both N-terminal and C-terminal
regions of the molecule. A' provides the first example of a nuclear protein that
possesses a leucine-rich amphipathic repeat motif, and the requirement of this
region for association with the U2 snRNP is compatible with a role in prote-
in : protein interactions. Currently, we are testing the proposal that the repeated
motify mediates specific protein: protein interactions of the U2 snRNP wihtin the
spliceosome.
Epitope Mapping of the Recombinant Human UlsnRNP 68 k Protein
H. Fujii1, K. Yamamoto1, H. Kohsaka1, Y. Tanaka’, H. Miura1, Y. Misaki1,
K. Nishioka2, and T. Miyamoto1
1 Department of Medicine and Physical Therapy, Faculty of Medicine,
University of Tokyo, Japan
2 Institute of Rheumatology, Tokyo Women’s Medical College, Tokyo, Japan
UlsnRNP 68 k protein is a major target molecule of anti-RNP antibodies
found in mixed connective tissue disease and other autoimmune diseases. In order
to investigate the mechanisms of autoantibody production and pathogenesis, we
have screened two different human cDNA libraries (fibroblast and fore skin) us-
ing a cDNA clone FL70K (kindly supplied by Drs. Luhrmann and Philipson).