DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0122
104
Molecular and Cell Biology of Autoantibodies and Autoimmunity
quence of the E protein to that of the other Sm proteins does not reveal any exten-
sive regions of sequence homology. However, the region of greatest homology to
the snRNP B and D proteins is at the carboxyl terminus of the E protein. Site-
directed monoclonal antibodies against the carboxyl terminus of the E protein
have now been produced. These antibodies show some cross-reaction with other
small RNA-binding proteins from HeLa cells. We are currently investigating the
identify of these proteins.
Eight of 10 genomic clones for the human E protein have the structure ex-
pected for processed pseudogenes. One clone contains an E protein coding se-
quence that spans 9 kb and is interrupted by four introns. The 5' flanking region
of this clone contains several sequence similarities to promoter elements found in-
vertebrate ribosomal protein genes and snRNA genes. Analysis of the promoter
region from this E gene by transfection of kidney 293 cells with CAT fusion con-
structs suggests that the regions of sequence similarity to snRNA and ribosomal
protein genes may have functional relevance.
The intron-containing gene for the E protein has been mapped to chromo-
some 1 by both hybridization to a panel of somatic cell hybrids and by in situ
hybridization. The in situ hybridization results suggest that the gene is located in
the region Iq2.5-q4.3. Thus, this gene is physically linked to a number of genes
coding for U 1 RNA.
A tenth genomic clone contains only the 3' terminal 113 nts of the E protein
cDNA sequence. The E protein homologous sequence is flanked on the 3' ter-
minus by a poly(A) tract of 16 nts and on the 5' end by a variant gene for another
component of the RNA processing machinery, U 6 snRNA. The coding region of
the U6 gene is 90% homologous to a previously characterized human U6 gene,
but lacks any homology to the 5' flanking elements previously shown to be re-
quired for efficient U 6 transcription. However, the variant U 6 gene is efficiently
transcribed by RNA polymerase III in a HeLa cell S100 extract, and can compete
with cloned tRNA genes for transcription factors. Additional interest in this
unusual genomic clone is generated by the finding that the U6-E protein se-
quences are located in the seventh intron of the human guanine nucleotide bind-
ing protein Gj3a.
Studies of the interaction of the E protein with other components of snRNPs
suggest that the E protein does not directly bind to snRNAs. Studies of the in-
teraction of the E protein with other cloned snRNP proteins are in progress.
Molecular and Cell Biology of Autoantibodies and Autoimmunity
quence of the E protein to that of the other Sm proteins does not reveal any exten-
sive regions of sequence homology. However, the region of greatest homology to
the snRNP B and D proteins is at the carboxyl terminus of the E protein. Site-
directed monoclonal antibodies against the carboxyl terminus of the E protein
have now been produced. These antibodies show some cross-reaction with other
small RNA-binding proteins from HeLa cells. We are currently investigating the
identify of these proteins.
Eight of 10 genomic clones for the human E protein have the structure ex-
pected for processed pseudogenes. One clone contains an E protein coding se-
quence that spans 9 kb and is interrupted by four introns. The 5' flanking region
of this clone contains several sequence similarities to promoter elements found in-
vertebrate ribosomal protein genes and snRNA genes. Analysis of the promoter
region from this E gene by transfection of kidney 293 cells with CAT fusion con-
structs suggests that the regions of sequence similarity to snRNA and ribosomal
protein genes may have functional relevance.
The intron-containing gene for the E protein has been mapped to chromo-
some 1 by both hybridization to a panel of somatic cell hybrids and by in situ
hybridization. The in situ hybridization results suggest that the gene is located in
the region Iq2.5-q4.3. Thus, this gene is physically linked to a number of genes
coding for U 1 RNA.
A tenth genomic clone contains only the 3' terminal 113 nts of the E protein
cDNA sequence. The E protein homologous sequence is flanked on the 3' ter-
minus by a poly(A) tract of 16 nts and on the 5' end by a variant gene for another
component of the RNA processing machinery, U 6 snRNA. The coding region of
the U6 gene is 90% homologous to a previously characterized human U6 gene,
but lacks any homology to the 5' flanking elements previously shown to be re-
quired for efficient U 6 transcription. However, the variant U 6 gene is efficiently
transcribed by RNA polymerase III in a HeLa cell S100 extract, and can compete
with cloned tRNA genes for transcription factors. Additional interest in this
unusual genomic clone is generated by the finding that the U6-E protein se-
quences are located in the seventh intron of the human guanine nucleotide bind-
ing protein Gj3a.
Studies of the interaction of the E protein with other components of snRNPs
suggest that the E protein does not directly bind to snRNAs. Studies of the in-
teraction of the E protein with other cloned snRNP proteins are in progress.