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Query: UNIPROT:P06889 (Mol)
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As shown by Southern blot analysis, the metallothionein-1 (MT-1) genes in rats comprise a multigene family. We present the sequence of the MT-1 structural gene and compare its features with other metallothionein genes. Three MT-1 pseudogenes which we sequenced apparently arose by reverse transcription of processed mRNA transcripts. Two of these, MT-1 psi a and MT-1 psi c, are retrogenes which derive from the MT-1 mRNA, having diverged from the MT-1 gene 6.9 and 2.6 million years ago, respectively. The third, MT-1 psi b, differs from the MT-1 cDNA by only three nucleotide alterations. Surprisingly, MT-1 psi b also preserves sequence homology for 142 base pairs 5' to the transcription initiation site of the parent gene; it contains a promoter sequence sufficient for specifying metal ion induction. We identified, by S1 nuclease mapping, an RNA polymerase II initiation site 432 base pairs 5' of the MT-1 transcription initiation site of the MT-1 structural gene which could explain the formation of the mRNA precursor to this pseudogene. We were unable to detect MT-1 psi b transcripts, either in liver tissue or after transfection. We conclude that the absence of detectable transcripts from this pseudogene is due to either a reduced level of transcription or the formation of unstable transcripts as a consequence of the lack of a consensus sequence normally found 3' of transcription termination in the MT-1 structural gene.
Mol Cell Biol 1986 Jan
PMID:Rat metallothionein-1 structural gene and three pseudogenes, one of which contains 5'-regulatory sequences. 302 30

We present the nucleotide sequence of the coding region of the rat c-rasH-1 gene and a partial sequence analysis of the rat c-rasH-2 gene. By comparing these sequences with the Harvey murine sarcoma virus ras gene, we predict that the p21 protein encoded by the Harvey virus differs from the cellular c-rasH-1-encoded p21 at only two amino acids; those at positions 12 and 59. Alterations at each of these positions may play a role in activating the viral p21 protein. The c-rasH-2 gene is likely to be a nonfunctional pseudogene because it lacks introns, cannot be activated to transform NIH 3T3 cells, and differs in sequence from both c-rasH-1 and v-rasH at several base pair positions.
Mol Cell Biol 1986 May
PMID:Nucleotide sequence of the two rat cellular rasH genes. 302 1

Two distinct chicken U4 RNA genes have been cloned and characterized. They are closely linked within 465 base pairs of each other and have the same transcriptional orientation. The downstream U4 homology is a true gene, based on the criteria that it is colinear with chicken U4B RNA and is expressed when injected into Xenopus laevis oocytes. The upstream U4 homology, however, contains seven base substitutions relative to U4B RNA. This sequence may be a nonexpressed pseudogene, but the pattern of base substitutions suggests that it more probably encodes a variant yet functional U4 RNA product not yet characterized at the RNA level. In support of this, the two U4 genes have regions of homology with each other in their 5'-flanking DNA at two positions known to be essential for the efficient expression of vertebrate U1 and U2 small nuclear RNA genes. In the case of U1 and U2 RNA genes, the more distal region (located near position-200 with respect to the RNA cap site) is known to function as a transcriptional enhancer. Although this region is highly conserved in overall structure and sequence among U1 and U2 RNA genes, it is much less conserved in the chicken U4 RNA genes reported here. Interestingly, short sequence elements present in the -200 region of the U4 RNA genes are inverted (i.e., on the complementary strand) relative to their usual orientation upstream of U1 and U2 RNA genes. Thus, the -200 region of the U4 RNA genes may represent a natural evolutionary occurrence of an enhancer sequence inversion.
Mol Cell Biol 1986 Nov
PMID:Structural and functional analysis of chicken U4 small nuclear RNA genes. 302 18

A mouse adenine phosphoribosyltransferase (aprt) pseudogene that had previously been recovered from a BALB/c sperm DNA library possessed several unusual features. Its nucleotide sequence, like that of other processed pseudogenes, was colinear with its corresponding mRNA, but it was truncated at its 3' end and lacked a poly(A) tail. The pseudogene was 82% homologous with corresponding regions of the functional gene and had incurred mutations that included transitions, transversions, deletions, and a point insertion. Even though the pseudogene was truncated within the protein-coding region of the corresponding functional gene, it was flanked at both ends by 13-base-pair direct repeats. Curiously, the direct repeats exhibited homology to APRT mRNA at the site of pseudogene divergence. The pseudogene appeared to be common to BALB/c and A/J mice, but it was contained on a 3-kilobase EcoRI fragment in the former strain and a 4.5-kilobase EcoRI fragment in the latter. The BALB/c and apparently the A/J pseudogene both mapped to chromosome 8, which also contains the functional aprt gene. The DNA sequences immediately surrounding the pseudogene in the two strains appeared to be similar, suggesting that the BALB/c and A/J pseudogenes are allelic. However, DNA sequences more distal to the pseudogene in the two strains appeared to vary. Thus, the EcoRI polymorphism was not due to simple loss of an EcoRI site, but was more complex. The pattern of flanking restriction sites was different for each of several enzymes, consistent with extensive DNA rearrangement. Double digests of BALB/c and A/J genomic DNAs revealed complex polymorphisms on both sides of the pseudogene. The results were consistent with insertion, deletion, or other rearrangement of DNA sequences that flank the pseudogene and suggest that this region of mouse chromosome 8 may be a region active for mutation or recombination.
Mol Cell Biol 1986 Dec
PMID:An unusual adenine phosphoribosyltransferase pseudogene is syntenic with its functional gene and is flanked by highly polymorphic DNAs. 302 40

A dispersed repetitive element named ingi, which is present in the genome of the protozoan parasite Trypanosoma brucei, is described. One complete 5.2-kilobase element and the ends of two others were sequenced. There were no direct or inverted terminal repeats. Rather, the ends consisted of two halves of a previously described 512-base-pair transposable element (G. Hasan, M.J. Turner, and J.S. Cordingley, Cell 37:333-341, 1984). Oligo(dA) tails and possible insertion site duplications suggested that ingi is a retroposon. The sequenced element appears to be a pseudogene copy of an original retroposon with one or more open reading frames occupying most of its length. Significant homologies of the encoded amino acid sequences with reverse transcriptases and mammalian long interpersed nuclear element sequences suggest a remote evolutionary origin for this kind of retroposon.
Mol Cell Biol 1987 Apr
PMID:Ingi, a 5.2-kb dispersed sequence element from Trypanosoma brucei that carries half of a smaller mobile element at either end and has homology with mammalian LINEs. 303 21

A chicken calmodulin pseudogene with no introns was previously shown to hybridize under stringent conditions with an mRNA species present in skeletal and cardiac muscles, yet it would not hybridize to calmodulin mRNA (J. P. Stein, R. P. Munjaal, L. Lagace', E. C. Lai, B. W. O'Malley, and A. R. Means, Proc. Natl. Acad. Sci. USA 80:6485-6489, 1983). Using the pseudogene as a probe, we isolated a full-length cDNA corresponding to this mRNA from a chicken breast muscle library and showed by sequence analysis that it encodes slow-muscle troponin C and not the pseudogene product. Hybridization between the calmodulin pseudogene and slow-muscle troponin C cDNA is due to a short region of high homology in those nucleotides that encode helices B and C of troponin C and calmodulin. Genomic Southern analysis showed the calmodulin pseudogene and the gene for slow-muscle troponin C to exist as distinct single copies.
Mol Cell Biol 1987 Apr
PMID:The nontranscribed chicken calmodulin pseudogene cross-hybridizes with mRNA from the slow-muscle troponin C gene. 303 28

Divergence dates among primates were estimated by molecular clock analysis of DNA sequence data. A molecular clock of eta-globin pseudogene was calibrated by setting the date of divergence between Catarrhini and Platyrrhini at 38 million years (Myr) ago. The clock gave dates of 25.3 +/- 2.4, 11.9 +/- 1.7, 5.9 +/- 1.2, and 4.9 +/- 1.2 Myr ago ( +/- refers to standard error) for the separation of rhesus monkey, orangutan, gorilla, and chimpanzee, respectively, from the line leading to humans. In placing confidence intervals of the estimates in a robust way, a bootstrap method was used. The 95% confidence intervals are 20.5-29.5, 9.0-14.8, 4.1-7.8, and 3.1-7.0 Myr ago for the separation of rhesus monkey, orangutan, gorilla, and chimpanzee, respectively. By a molecular clock dating of the Prosimii-Anthropoidea splitting, it was suggested that the evolutionary rate of the eta-globin gene was high early in primate evolution and subsequently decreased in the line of Anthropoidea. And, by a relative rate test using bootstrap sampling, the possibility of further decrease of the rate (more than 10%) in the line of Hominoidea compared with that of Cercopithecoidea was suggested. Therefore, the above dating of the splittings within Hominoidea may be biased slightly toward younger dates. On the other hand, mitochondrial DNA (mtDNA) seems to have evolved in mammals with a more uniform rate than the eta-globin gene. The ratio of the dates of orangutan splitting to chimpanzee splitting is larger for the mtDNA clock than that for the eta-globin clock, suggesting the possibilities of mtDNA introgression among the early hominids and the early African apes, and/or of mtDNA polymorphism within the common ancestral species of orangutan and the African apes that obscures the date of the true species separation of orangutans.
J Mol Evol 1987
PMID:Man's place in Hominoidea as inferred from molecular clocks of DNA. 312 31

The structure of one of the V kappa gene-containing regions of the locus coding for the human immunoglobulin light chains of the kappa type is described. This so-called B region contains three genes: B1, B2 and B3. According to its sequence B1 is a pseudogene which does not fit well into the present subgroup classification. In lymphoid cell lines the B1 gene region is frequently deleted. B2 and B3 are the previously reported EV15 and V kappa IV genes. The transcriptional polarity of the B1 gene is found to be opposite to one of the B2 and B3 genes. This observation together with the fact that the B region is proximal to the J kappa C kappa gene segment leads to the conclusions to the mechanism of the V kappa-J kappa recombination and allows us to explain the formation of the recombination products in a particular cell line by two consecutive inversions.
Mol Immunol 1988 May
PMID:The J kappa proximal region of the human K locus contains three uncommon V kappa genes which are arranged in opposite transcriptional polarities. 313 58

In order to examine the number and organization of the immunoglobulin lambda light chain genes of the rat, we have used mouse lambda chain cDNA probes to isolate hybridizing fragments from a partial EcoRI rat liver DNA library. We have determined the partial nucleotide sequence of two such clones. One clone, containing a 5.8 kb EcoRI insert which hybridizes to both mouse C lambda 1 and C lambda 2 probes, includes an apparently expressible C lambda 2-like gene as well as a C lambda 1-like pseudogene (psi C lambda 1.1), arranged similarly to the mouse C lambda gene complexes. Sequence analysis of a second cloned EcoRI fragment (1.15 kb in length) revealed part of a second C lambda 1-like pseudogene (psi C lambda 1.2), the coding regions of both pseudogenes being interrupted by multiple frame-shifting size differences. In the case of psi C lambda 1.2, the degree of sequence identity with mouse C lambda 1 drops abruptly immediately following the termination codon, suggesting that translocation events have played a role in its generation. These two rat pseudogenes, and the mouse C lambda 4 pseudogene, clearly have been rendered unexpressible by separate evolutionary events. Comparisons between C lambda coding and non-coding regions of rats and mice indicate that some of the unusual patterns of divergence we have observed in recently diverged Ck genes may exist in C lambda genes as well.
Mol Immunol 1988 Oct
PMID:Two pseudogenes among three rat immunoglobulin lambda chain genes. 314 24

The patterns of synonymous codon usage in 91 Drosophila melanogaster genes have been examined. Codon usage varies strikingly among genes. This variation is associated with differences in G+C content at silent sites, but (unlike the situation in mammalian genes) these differences are not correlated with variation in intron base composition and so are not easily explicable in terms of mutational biases. Instead, those genes with high G+C content at silent sites, resulting from a strong "preference" for a particular subset of the codons that are mostly C-ending, appear to be the more highly expressed genes. This suggests that G+C content is reduced in sequences where selective constraints are weaker, as indeed seen in a pseudogene. These and other data discussed are consistent with the effects of translational selection among synonymous codons, as seen in unicellular organisms. The existence of selective constraints on silent substitutions, which may vary in strength among genes, has implications for the use of silent molecular clocks.
Mol Biol Evol 1988 Nov
PMID:"Silent" sites in Drosophila genes are not neutral: evidence of selection among synonymous codons. 314 82


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