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Results for “pseudogene”

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At least 955 records · Page 53Linked to original sources
PubMed1985

A processed pseudogene in an intron of the HLA-DP beta 1 chain gene is a member of the ribosomal protein L32 gene family.

A sequence in an intron of the human HLA-DP beta 1 gene was identified by its homology to the gene encoding ribosomal protein L32 (rpL32). It lacked introns indicating that it was derived from a processed rpL32 mRNA transcript. A human cDNA clone encoding rpL32 was isolated and compared to this human pseudogene and to several related mouse sequences, one of which is contained in an intron of the murine dihydrofolate reductase gene. Comparison of these sequences revealed that they were more related within species than between, suggesting that they became inserted in the genome after man and mouse diverged.

Animals↗
PubMed1986

The mRNA and RNA-copy pseudogenes encoding TM30nm, a human cytoskeletal tropomyosin.

We have determined the sequence of a 2.5 kb mRNA in human fibroblasts encoding a 248 amino acid cytoskeletal tropomyosin. The protein product of this mRNA is TM30nm, one of five tropomyosin-like proteins in human fibroblasts. The structural gene encoding this mRNA can also produce a 1.3 kb mRNA encoding a 285 amino acid skeletal muscle alpha-tropomyosin by tissue-specific alternative mRNA splicing. However, the multiple RNA-copy pseudogenes of this gene family are derived largely if not exclusively from transcripts processed according to the pattern observed in non-muscle cells.

Amino Acid Sequence↗
PubMed1986

A processed chicken pseudogene (CPS1) related to the ras oncogene superfamily.

We describe the first polyA-containing processed pseudogene reported in the chicken. It includes a 0.52 kb open reading frame which could encode a 175 amino acid protein. The putative protein shows extensive homology to the ras oncogene superfamily, being most closely related to the yeast protein YP2. It is one of the two most divergent members of the ras superfamily yet described and is the most homologous of any ras-related protein to the G-protein alpha-transducin. The chicken genome contains at least one other gene highly homologous to CPS1; at least one member of the CPS1 family is active, but only early in chicken development. This pattern of expression, and the presence of mutations in regions known to activate human c-ras genes to oncogenicity, suggest that CPS1 may represent a new oncogene family.

Animals↗
PubMed1981

Transcription of the beta-like globin genes and pseudogenes of the goat in a cell-free system.

We have examined the transcription in a cell-free system of all the members of a highly regulated gene family, the beta-like hemoglobin genes of the goat. These five genes, which code for embryonic, fetal, juvenile, and adult beta-globin proteins, are all transcribed to roughly the same extent in the in vitro system. In all cases initiation of transcription is accurate. However, two goat beta-globin pseudogenes, as well as several artificially constructed deletion mutants, are not transcribed in vitro. A common feature of the transcriptionally inactive genes is the lack of an AT-rich consensus sequence just upstream of the presumptive initiation site.

Animals↗
PubMed1988

X/Y translocation in a family with X-linked ichthyosis, chondrodysplasia punctata, and mental retardation: DNA analysis reveals deletion of the steroid sulphatase gene and translocation of its Y pseudogene.

We describe a family with two male members showing an X/Y translocation (karyotype: 46,Y,der(X)t(X;Y)(p22;q11]. At physical examination both patients showed ichthyosis, mental retardation and dysmorphic features. Chondrodysplasia punctata and short stature were present in one case. Direct DNA analysis, using a steroid sulphatase cDNA probe, was performed in one patient, his mother and sister, both carriers of the translocation. We found that the translocated region of the Y chromosome includes the steroid sulphatase pseudogene. These results suggest that in our patients the X/Y translocation may be derived from a recombinational event between homologous regions located on the short arm of the X chromosome and the long arm of the Y chromosome. Clinical and molecular studies on the present family add further information for the construction of a tentative physical map of the distal Xp.

Child↗
PubMed1982

Diverse mechanisms in the generation of human beta-tubulin pseudogenes.

The sequence of two human beta-tubulin pseudogenes is described. One contains an intervening sequence but lacks sequences encoding the 55 N-terminal amino acids of the polypeptide chain. A second has no introns but has a polyadenylate signal and an oligoadenylate tract at its 3' end, and it is flanked by a short direct repeat. These sequences have arisen by different mechanisms, including one that probably involves reverse transcription of a processed messenger RNA and reintegration of the complementary DNA copy into the genome.

Base Sequence↗
PubMed1984

Characterization of the expressed gene and several processed pseudogenes for the mouse ribosomal protein L30 gene family.

Five cloned genes encoding the mouse ribosomal protein L30 were isolated from a recombinant DNA library and characterized by restriction mapping and nucleotide sequence analysis. Only one of these genes has introns and is expressed; the others are inactive processed pseudogenes. The expressed gene consists of five exons and four introns spanning 2,723 nucleotides. Transcripts of this gene are processed into the mature L30 mRNA by pathways that exhibit both constraints and flexibility with regard to the order of intron excision. The L30 mRNA which is 457 to 468 nucleotides in length excluding the polyadenylic acid tail, exhibits some microheterogeneity at its 3' end and encodes a basic protein of 115 amino acids. The 5' portion of the rpL30 gene has some novel features which are remarkably similar to the previously characterized mouse rpL32 gene. These include homologous sequences in the -60 to -340 region, the absence of a good TATA consensus sequence, and the presence of a palindromic pyrimidine sequence that spans the cap site.

Animals↗
PubMed1984

The gene and the pseudogene for mouse p53 cellular tumor antigen are located on different chromosomes.

The chromosomal assignments of the two genes encoding the murine p53 cellular tumor antigen were determined by using a panel of mouse-Chinese hamster somatic cell hybrid clones and a mouse p53-specific cDNA clone. One gene, probably the functional member of the family, was found to be on chromosome 11. The other gene, which is probably a processed pseudogene, was assigned to chromosome 14. The potential relevance of these findings to documented cases of chromosome 11 trisomy are also discussed.

Animals↗
PubMed2005

LINEs, SINEs and processed pseudogenes: parasitic strategies for genome modeling.

Two major classes of retrotransposons have invaded eukaryotic genomes: the LTR retrotransposons closely resembling the proviral integrated form of infectious retroviruses, and the non-LTR retrotransposons including the widespread, autonomous LINE elements. Here, we review the modeling effects of the latter class of elements, which are the most active in humans, and whose enzymatic machinery is subverted to generate a large series of "secondary" retroelements. These include the processed pseudogenes, naturally present in all eukaryotic genomes possessing non-LTR retroelements, and the very successful SINE elements such as the human Alu sequences which have evolved refined parasitic strategies to efficiently bypass the original "protectionist" cis-preference of LINEs for their own retrotransposition.

Animals↗
PubMed2006

Evolution of glyoxylate cycle enzymes in Metazoa: evidence of multiple horizontal transfer events and pseudogene formation.

BACKGROUND: The glyoxylate cycle is thought to be present in bacteria, protists, plants, fungi, and nematodes, but not in other Metazoa. However, activity of the glyoxylate cycle enzymes, malate synthase (MS) and isocitrate lyase (ICL), in animal tissues has been reported. In order to clarify the status of the MS and ICL genes in animals and get an insight into their evolution, we undertook a comparative-genomic study. RESULTS: Using sequence similarity searches, we identified MS genes in arthropods, echinoderms, and vertebrates, including platypus and opossum, but not in the numerous sequenced genomes of placental mammals. The regions of the placental mammals' genomes expected to code for malate synthase, as determined by comparison of the gene orders in vertebrate genomes, show clear similarity to the opossum MS sequence but contain stop codons, indicating that the MS gene became a pseudogene in placental mammals. By contrast, the ICL gene is undetectable in animals other than the nematodes that possess a bifunctional, fused ICL-MS gene. Examination of phylogenetic trees of MS and ICL suggests multiple horizontal gene transfer events that probably went in both directions between several bacterial and eukaryotic lineages. The strongest evidence was obtained for the acquisition of the bifunctional ICL-MS gene from an as yet unknown bacterial source with the corresponding operonic organization by the common ancestor of the nematodes. CONCLUSION: The distribution of the MS and ICL genes in animals suggests that either they encode alternative enzymes of the glyoxylate cycle that are not orthologous to the known MS and ICL or the animal MS acquired a new function that remains to be characterized. Regardless of the ultimate solution to this conundrum, the genes for the glyoxylate cycle enzymes present a remarkable variety of evolutionary events including unusual horizontal gene transfer from bacteria to animals.

Journal Article↗
PubMed2002

Confirmation of the potential usefulness of two human beta globin pseudogene markers to estimate gene flows to and from sub-Saharan Africans.

Two polymorphic sites, -107 and -100 with respect to the "cap" site of the human beta globin pseudogene, recently discovered in our laboratory, turned out to have an ethnically complementary distribution. The first site is polymorphic in Europeans, North Africans, Indians (Hindu), and Oriental Asians, and monomorphic in sub-Saharan Africans. Conversely, the second site is polymorphic in sub-Saharan African populations and monomorphic in the aforementioned populations. Here we report the gene frequencies of these two polymorphic sites in nine additional populations (Egyptians, Spaniards, Japanese, Chinese, Filipinos, Vietnamese, Africans from Togo and from Benin, and Pygmies), confirming their ethnospecificity and, through the analysis of these two markers in Oromo and Amhara of Ethiopia (two mixed populations), their usefulness in genetic admixture studies. Moreover, we studied another marker polymorphic in sub-Saharan African populations only, a TaqI restriction fragment length polymorphism located in the same region as the present markers, demonstrating the absence of linkage disequilibrium between it and the -100 site, so that we can exclude that the information they provide is redundant.

Africa South of the Sahara↗
PubMed2005

Pseudogenization of a sweet-receptor gene accounts for cats' indifference toward sugar.

Although domestic cats (Felis silvestris catus) possess an otherwise functional sense of taste, they, unlike most mammals, do not prefer and may be unable to detect the sweetness of sugars. One possible explanation for this behavior is that cats lack the sensory system to taste sugars and therefore are indifferent to them. Drawing on work in mice, demonstrating that alleles of sweet-receptor genes predict low sugar intake, we examined the possibility that genes involved in the initial transduction of sweet perception might account for the indifference to sweet-tasting foods by cats. We characterized the sweet-receptor genes of domestic cats as well as those of other members of the Felidae family of obligate carnivores, tiger and cheetah. Because the mammalian sweet-taste receptor is formed by the dimerization of two proteins (T1R2 and T1R3; gene symbols Tas1r2 and Tas1r3), we identified and sequenced both genes in the cat by screening a feline genomic BAC library and by performing PCR with degenerate primers on cat genomic DNA. Gene expression was assessed by RT-PCR of taste tissue, in situ hybridization, and immunohistochemistry. The cat Tas1r3 gene shows high sequence similarity with functional Tas1r3 genes of other species. Message from Tas1r3 was detected by RT-PCR of taste tissue. In situ hybridization and immunohistochemical studies demonstrate that Tas1r3 is expressed, as expected, in taste buds. However, the cat Tas1r2 gene shows a 247-base pair microdeletion in exon 3 and stop codons in exons 4 and 6. There was no evidence of detectable mRNA from cat Tas1r2 by RT-PCR or in situ hybridization, and no evidence of protein expression by immunohistochemistry. Tas1r2 in tiger and cheetah and in six healthy adult domestic cats all show the similar deletion and stop codons. We conclude that cat Tas1r3 is an apparently functional and expressed receptor but that cat Tas1r2 is an unexpressed pseudogene. A functional sweet-taste receptor heteromer cannot form, and thus the cat lacks the receptor likely necessary for detection of sweet stimuli. This molecular change was very likely an important event in the evolution of the cat's carnivorous behavior.

Journal Article↗
PubMed1999

A comparative study of rat and human Tmp21 (p23) reveals the pseudogene-like features of human Tmp21-II.

Tmp21 (p23) is involved in biosynthetic transport from the endoplasmic reticulum to the Golgi complex. We have recently characterized two cDNA-variants of human Tmp21, the Tmp21-isoforms-I and -II. Because of the lack of cDNA sequence data and protein expression data, it was not clear if Tmp21-II encodes a functional Tmp21-protein. Here we describe the cloning of the full length human Tmp21-II transcript. The putative open reading frame of Tmp21-II contains a reading frame jump and a nonsense mutation in comparison to all other Tmp21-I (p23) members. Our data indicate that hum-Tmp21-II is transcribed, but not translated. We conclude that Tmp21-II cDNA derives from a neutral pseudogene, which originates from a duplication event of the human Tmp21-isoform-I.

Amino Acid Sequence↗
PubMed1987

DNA sequence of a human Sm autoimmune antigen. The multigene family contains a processed pseudogene.

The sequence of a complementary DNA clone coding for a human autoimmune antigen has been determined. This DNA sequence predicts the amino acid sequence of a small protein ("E") which is associated with small nuclear RNA in human cells. Analysis of the predicted protein sequence suggests that the E protein is not closely related to other nucleic acid binding proteins. Screening of a human genomic DNA library has led to the isolation of several members of the E protein multigene family. Sequence analysis of one member of this family reveals that it is flanked by direct repeats and contains several mutations. One of these mutations, an insertion, terminates the long open reading frame. These features are compatible with the designation of this sequence as a processed pseudogene.

Amino Acid Sequence↗
PubMed1985

Structure and expression of two human metallothionein-I isoform genes and a related pseudogene.

Three members of the human metallothionein-I gene family have been cloned and characterized. Two of the genes encode closely related but distinct metallothionein-I subtypes. Both of these genes are functional as shown by their transcription in cultured hepatoblastoma cells and by their ability to render transfected cells resistant to cadmium toxicity. The cotranscription of these nonallelic genes shows that the previously observed microheterogeneity of metallothionein-I protein preparations is due to the expression of distinct gene products. The third clone is incapable of encoding a typical metallothionein due to an early termination codon and two nonconservative amino acid replacements. This nonfunctional pseudogene retains introns. Evolutionary comparisons reveal conserved DNA sequences in both the coding and regulatory regions of these genes.

Amino Acid Sequence↗
PubMed1985

The human phosphoglycerate kinase multigene family. HLA-associated sequences and an X-linked locus containing a processed pseudogene and its functional counterpart.

Several phosphoglycerate kinase genes were previously detected in the human genome by blot hybridization with a phosphoglycerate kinase cDNA probe. Using subcloned fragments of the cDNA we estimate the presence of four independent phosphoglycerate kinase genes. These genes have been mapped to both the human X chromosome (band q13) and chromosome 6 (p12-21.1) using a panel of human-rodent somatic cell hybrids and by chromosomal in situ hybridization. The genomic distribution of phosphoglycerate kinase sequences is conserved in man and mouse, not only for the X chromosome, but also for linkage to the respective major histocompatibility complexes. Molecular cloning of X-linked phosphoglycerate kinase sequences led to the identification of a novel intronless phosphoglycerate kinase pseudogene which is localized proximal to the active gene on the X chromosome.

Base Sequence↗
PubMed1983

Genes and pseudogenes for mouse U1 and U2 small nuclear RNAs.

Regions of the mouse genome homologous to U1 and U2 small nuclear RNAs have been isolated. The U1 regions are identified as pseudogenes on the basis of: 1) insertions, deletions, and substitutions in the sequence of the DNA as compared with that of U1 RNA; 2) absence of complementary RNA in mouse tissues; and 3) lack of expression upon microinjection in Xenopus oocyte nuclei. A U2 region is identified as a gene on the basis of near identity of sequence with U2 RNA and capacity to direct the synthesis of U2-like RNA in Xenopus oocyte nuclei. Both U1 and U2 sequences are repeated in the mouse genome, the U2 sequences analyzed here in an inverted repeat arrangement.

Animals↗