Cloning and characterization of two processed pseudogenes and the cDNA for the murine U1 snRNP-specific protein C
Genes for the snRNP proteins U1-70K, U1-A, Sm-B′/B, Sm-D1 and Sm-E have been isolated from various metazoan species. The genes for Sm-D1 and Sm-E, which were isolated from a murine and human source respectively, appear to belong to a multigene family. It has been suggested that also for the mammalia...
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Published in | Gene Vol. 184; no. 2; pp. 273 - 278 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
15.01.1997
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Subjects | |
Online Access | Get full text |
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Summary: | Genes for the snRNP proteins U1-70K, U1-A, Sm-B′/B, Sm-D1 and Sm-E have been isolated from various metazoan species. The genes for Sm-D1 and Sm-E, which were isolated from a murine and human source respectively, appear to belong to a multigene family. It has been suggested that also for the mammalian U1-C protein such a multigene family exists. With the human
U1-C cDNA as a probe, two genes containing sequences homologous to the probe sequence were isolated from a mouse genomic library. Simultaneously, a murine
U1-C cDNA was isolated from a mouse cDNA library. This 0.74 kb cDNA contains an open reading frame (ORF) of 477 bp encoding a polypeptide of 159 amino acids (aa) which differs at only one position (position 65) from the human U1-C protein. One of the isolated
U1-C genes contains an ORF as well and shares 92% nucleotide sequence identity with the mouse
U1-C cDNA. The features of this gene, in particular the absence of introns, the acquisition of a 3′ poly(A) tail and flanking direct repeats, indicate that it represents a processed pseudogene. At the predicted aa sequence level, substitutions of conserved residues at functionally important positions are observed, strongly suggesting that expression of this gene would not lead to a functional polypeptide. The second
U1-C gene appeared to be a pseudogene as well because it is also intronless and contains a frameshift mutation compared to the ORF in the mouse
U1-C cDNA. The characterization of these two pseudogenes points to the existence of a
U1-C multigene family in mice. Furthermore, comparison of aa sequences of the murine, human and
Xenopus U1-C shows that the protein is highly conserved through evolution. Since the
Xenopus U1-C differs from the two mammalian counterparts solely at a number of positions in the C-terminal region, it can be concluded that aa changes are less well tolerated in the N-terminal region of U1-C than in the rest of the protein. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0378-1119 1879-0038 |
DOI: | 10.1016/S0378-1119(96)00612-9 |