Genomic organisation and alternative splicing of mouse and human thioredoxin reductase 1 genes
© Osborne and Tonissen; licensee BioMed Central Ltd. 2001
Received: 28 August 2001
Accepted: 22 November 2001
Published: 22 November 2001
Thioredoxin reductase (TR) is a redox active protein involved in many cellular processes as part of the thioredoxin system. Presently there are three recognised forms of mammalian thioredoxin reductase designated as TR1, TR3 and TGR, that represent the cytosolic, mitochondrial and novel forms respectively. In this study we elucidated the genomic organisation of the mouse (Txnrd1) and human thioredoxin reductase 1 genes (TXNRD1) through library screening, restriction mapping and database mining.
The human TXNRD1 gene spans 100 kb of genomic DNA organised into 16 exons and the mouse Txnrd1 gene has a similar exon/intron arrangement. We also analysed the alternative splicing patterns displayed by the mouse and human thioredoxin reductase 1 genes and mapped the different mRNA isoforms with respect to genomic organisation. These isoforms differ at the 5' end and encode putative proteins of different molecular mass. Genomic DNA sequences upstream of mouse exon 1 were compared to the human promoter to identify conserved elements.
The human and mouse thioredoxin reductase 1 gene organisation is highly conserved and both genes exhibit alternative splicing at the 5' end. The mouse and human promoters share some conserved sequences.
The thioredoxin system is comprised of thioredoxin (Trx) and thioredoxin reductase (TR) and plays an important role in maintaining the redox state of the cell . This system is involved in many cellular functions including synthesis of deoxyribonucleotides , redox control of transcription factors , protection against oxidative stress , cell growth and cancer . The reduced form of Trx is maintained by TR, an enzyme that contains a redox active disulphide group and a FAD molecule that uses the reducing power of NADPH [6, 7]. Presently, there are three recognised forms of mammalian thioredoxin reductase: TR1, TR3 and TGR, that share a similar domain organisation and all contain selenocysteine [8–14]. TR1 was the first thioredoxin reductase to be characterised and is known as the cytosolic form . TR3 is the mitochondrial form and is also known as TrxR2 [9–11]. TGR, previously known as the novel form of thioredoxin reductase (or TR2) functions as a Trx and GSSG reductase [11, 12]. In this study, we focus upon the cytosolic form of mouse thioredoxin reductase (mTR1) and human thioredoxin reductase (hTR1). The mouse Txnrd1 gene is located on chromosome 10 and yields a cDNA sequence approximately 3200 bp long. This sequence encodes a protein with 499 amino acids and a molecular mass of 54.5 kDa . The human TXNRD1 gene is located on chromosome 12  and the first cDNA sequence reported was 3826 bp and encoded a protein of 495 amino acids with a molecular mass of 54.1 kDa . Recently it was reported that the mouse Txnrd1 gene is alternatively spliced, producing three isoforms of mouse Txnrd1 mRNA that vary in their 5' sequences but have common downstream sequences . Also recently, the human TXNRD1 gene has been reported to exhibit possible alternative splicing around its first exon .
Here we report the genomic organisation of the human and mouse thioredoxin reductase 1 genes, subsequently detailing the alternative splicing pattern of the first exon in both species. We also present a potential mouse Txnrd1 promoter region and compare this genomic DNA sequence with the recently studied TXNRD1 gene promoter  to identify conserved sequences.
Results and Discussion
Mouse Txnrd1 genomic organisation
Intron/Exon boundaries of human TXNRD1 and mouse Txnrd1 genes
Exon Number TXNRD1/Txnrd1
Intron Numbera TXNRD1/Txnrd 1
Human TXNRD1 Gene
Mouse Txnrd1 Gene
Exon size (bp)
Intron size (kb)
Sequence at intron/EXON/intron junctionb
Exon size (bp)
Intron size (kb)
Sequence at intron/EXON/intron junctionb
ctgcag TCCTGA--ATTCTTgt aagc
ctgcag TCCTGA--CATGTGgt aagt
acacag AGGACG---TTGAAGgt agga
ccacag TGCTTT-----GGGCTGgt aagt
ctttag GCTTAT-------GCTAAGgc aagg
ctgcag CCGAAC-------GCTAAGgc aaga
ttccag GAGGCA-----GATGGGgt aagc
tcccag GAGGCA-------GATGGGgt gagt
ttgtag GTCTTG-----AGACAGgt atga
ttgcag GTCTCG---------ACACAGgt gtgg
atacag TTAAGC-----ATTAAGgt aatt
acgcag TGAAGC-------ATTGTGgt aatt
tgttag GCAACA------CAGCAGgt aaag
ttgcag GCGACA--------CAGCAGgt gggt
ccccag TGATGA----ATTAAAgt aagt
ctccag TGATGA--------ACGAAAgt aagt
ttacag GTTGAA-----AATACGgt aagg
ttgtag ATTGAA---------AACACAgt aagg
tttcag GTGATG------TGAAAAgt aaga
ttttag GTGTTG----------CGAAAAgt aagg
ttgcag GACTGG-----GTCAAGgt gagt
ttgcag AACCGG-------GTCAAAgt gaga
aaacag TGTGAC----ATTGAGgt aagt
acacag TGTGAC-------ATTGAAgt aagt
tcttag GTTTAC-------GACAATgt aagt
ttccag GTTTAC---------GACGATgt aagt
ccttag GAACGT-----GCAGAGgt gggt
tcttag GAACGT---------GCAGAGgt gagt
ctgcag GTATTC-----GGTTAA 3'UT
ctgcag ATATTC--------GGTGAAgt gcNg
Human TXNRD1 genomic organisation
To determine the genomic structure of the human TXNRD1 gene, the human genome data from the NCBI database http://www.ncbi.nlm.nih.gov was searched using the TXNRD1 cDNA  sequence. Alignments were used to establish intron/exon junctions, and these results confirmed through the adherence of predicted splice signals to the AG/GT rule  and by comparisons made with the mouse intron/exon junctions described above. The cDNA sequences for mouse and human thioredoxin reductase are approximately 80% homologous, and the human  and mouse  thioredoxin genes have an identical genomic organisation. Therefore we predicted that the human and mouse thioredoxin reductase genes would also have a similar organisation. After searching approximately 100 kb of human TXNRD1 genomic DNA sequence, all exons were mapped.
The mapping of the human TXNRD1 gene is detailed in Table 1. Exon lengths range from the shortest, exon 1a (42 bp), to the longest, exon 3b (341 bp). The start codon is located in exon 4, however another ATG is found in exon 1 and may be utilised in at least one mRNA isoform . The stop codon is positioned in exon 16, as is the 3'UT region. Intron sizes vary greatly from the shortest, intron 10 (917 bp), to the longest mapped intron, intron 12 (26.97 kb). Table 1 also lists the intron/exon splice signals which all conform to the AG/GT rule , except intron 4. Like intron 4 in the mouse Txnrd1 gene, the human 5' splice donor contains a GC instead of GT. The occurrence of this splice signal deviation in both mouse and human thioredoxin reductase intron 4 sequences is interesting since the 5' region of both genes are involved in alternative splicing and this could represent a potential regulatory site.
Alternative splicing of mouse and human TXNRD1 genes
Recent reports of alternative splicing in both the mouse [17, 22] and human  thioredoxin reductase genes lead us to investigate the link between splicing events and genomic organisation. This investigation was carried out through comparisons of mouse and human thioredoxin reductase expressed sequence tags (EST) with the genomic organisation as described in this report.
Alternative splicing of mouse Txnrd1 gene
• Isoform I
As reported by Sun et al , isoform I contains the ATG start codon positioned within exon 4 and translation of the resulting sequence produces the first reported mouse TR1 protein of 54.5 kDa .
• Isoform II
With respect to isoform II, we noted that ESTs (for example, accession number AI956288) containing exon 2 always displayed exon 1 immediately upstream, or did not extend far enough to be informative. Thus isoform II appears to contain exons 1, 2, 4, 5, 6, 7 etc (Figure 1). The only ATG start codon in the correct reading frame is located in exon 4, hence translation of this isoform would also yield the 54.5 kDa mouse TR1 protein .
• Isoform III
With respect to form III, ESTs containing exon 3 (accession numbers AA168412, AI607108) were aligned with mouse Txnrd1 genomic DNA sequences in order to establish the intron/exon junctions. Alignment of a mouse Txnrd1 EST containing exon 3 (accession number AI607108) with mouse genomic Txnrd1 sequence (Trace Archive 22011035) showed exon 3 is actually comprised of two exons, designated as exons 3a and 3b in this study. The splicing signals around exon 3b are consistent with the AG/GT rule . Exon 3a was aligned with the mouse genomic Txnrd1 DNA sequence (Trace Archive 18378992) to confirm a consensus splice sequence at the 5' splice donor site to form the intron between exon 3a and 3b. The 5' end of exon 3a could not be accurately defined since the 5'end of isoform III has not been accurately mapped. All ESTs containing exon 3 sequences always contain both exon 3a and 3b and therefore isoform III is predicted to contain exons 3a, 3b, 4, 5, 6, 7 etc (Figure 1). Two ATG start codons in the same reading frame are present in exons 3b and 4. Translation from the start codon encoded in exon 4 would produce the original 54.5 kDa protein, however use of the start codon in exon 3b yields a protein with a predicted molecular mass of 67 kDa. This 67 kDa protein coincides with the 67 kDa mTR1 protein previously reported .
Alternative splicing of human TXNRD1 gene
Alternative splicing of the human TXNRD1 gene was investigated based on that already determined for the mouse Txnrd1 gene and also on recent reports of possible alternative splicing in the human TXNRD1 gene [17, 18]. The Arner group  reported three isoforms of human TXNRD1 mRNA – I, II and III, however these isoforms do not align with the three mouse mRNA isoforms previously discussed. In this report the human TXNRD1 isoforms are numbered according to structural and sequence similarity displayed with the mouse Txnrd1 isoforms where possible. Subsequently the isoforms I, II and III reported by the Arner group are denoted here as isoforms V, II and I (respectively). In addition to the isoforms reported by the Arner group we identified two further isoforms (isoforms IV and VI) and proposed another (isoform III), that would align with the mouse isoform III.
• Isoform I
Isoform I contains exons 1, 2, 4, 5, 6, 7 etc (accession number BF182740)  and represents the human TXNRD1 cDNA sequence first reported . There are two ATG start codons in the correct reading frame in exons 1 and 4. The ATG in exon 4 directs translation of the orginal 54.1 kDa hTR1 protein . Translation of this mRNA isoform from the ATG in exon 1 yields a protein with a predicted molecular mass of approximately 60 kDa . This protein coincides with a 60 kDa hTR1 protein previously reported .
• Isoform II
Isoform II is comprised of exons 1, 4, 5, 6, 7 etc (accession number AU077310). The ATG start codon is in exon 4 and directs translation of the original 54.1 kDa hTR1 protein.
• Isoform III
An analysis of the reading frame in exon 3b revealed three in frame ATG codons that could potentially initiate translation. Translation of this mRNA isoform from the most 5' ATG start codon in exon 3b would produce a protein with a predicted molecular mass of approximately 67 kDa. A human TR1 protein with a mass of 67 kDa has been detected  substantiating the possibility that exon 3b is present in some mRNA transcripts. A search of the EST and nucleotide databases failed to identify any expressed sequences that contain exon 3b.
• Isoform IV
Isoform IV was discovered following an EST database search. This isoform contains exon 1A, 4, 5, 6, 7 etc (accession number AU132293). Exon 1A is a product of an internal splice site located within exon 1. This splice site generates a 42 bp fragment that corresponds to the 5' end of exon 1. There is one ATG start codon in the correct reading frame in exon 4 and translation from this ATG yields the original 54.1 kDa hTR1 protein .
• Isoforms V
This isoform contains exons 1A, 2, 4, 5, 6, 7 etc (accession number BG771986). The ATG start codon is in exon 4 and directs translation to produce the original 54.1 kDa human TR1 protein .
• Isoforms VI
Isoform VI was discovered via an EST database search. This isoform contains exons 2, 4, 5, 6, 7 etc (accession number BG772375) and the ATG codon is found in exon 4 where it directs translation to potentially produce the original 54.1 kDa TR1 protein . The EST that revealed this isoform extends a further 300 bp immediately upstream of the 5' end of exon 2. The nature of this 300 bp region is unknown as it did not display homology with human TXNRD1 cDNA sequences or any sequence in GenBank. Subsequently the 5' end of this isoform may not terminate with exon 2.
Potential thioredoxin reductase regulatory elements
The alternative splicing pattern utilised by both the TXNRD1 and Txnrd1 genes generate mRNA isoforms that are heterogenous at the 5' end. This alternative splicing presents consequences for possible gene regulation and location of control elements. Indeed Rundlof and co-workers  recently reported that the alternatively spliced mouse transcripts are expressed in a tissue specific manner. Currently the only genome information regarding transcriptional control of thioredoxin reductase 1 genes is available in the recent identification and characterisation of the core promoter for the human TXNRD1 gene . This core promoter of approximately 180 bp contains Oct 1, Sp1 and Sp3 binding sites and has an increased GC content, suggesting the human TXNRD1 gene is a house keeping gene. However this does not explain the response of TXNRD1 to cellular signalling since thioredoxin reductase protein and mRNA levels are known to increase quickly and significantly in human cells in response to exogenous agents. It is possible that the core promoter for the human TXNRD1 gene is accompanied by other promoter elements that have not yet been identified. Comparisons between mouse and human promoter regions may reveal these potential regulatory elements.
The mouse Txnrd1 mRNA isoform III does not contain exon 1, instead exon 3a is the most 5' exon. This infers that a potential promoter region may be present just upstream from exon 3a. This isoform encodes a 67 kDa protein that is expressed at lower levels  than the 54.5 kDa mouse TR1 protein first identified . The difference in expression levels of these two forms of mouse Txnrd1 may be a reflection of the use of alternate promoter regions. In the human gene exons 1 and 4 span approximately 28 kb and similarly an alternative promoter may exist in this region to direct transcription of mRNA isoforms that lack exon 1.
In conclusion we report the genomic organisation of mouse and human thioredoxin reductase 1 genes. These genes display a conserved genomic organisation as the coding regions of both genes have an almost identical exon/intron structure. Comparison of mouse and human 5' sequences allows possible regulatory elements to be identified and also in this study has enabled alternative splicing events at the 5' end of each gene to be reviewed and further defined. Further work will be required to link the different transcripts with specific promoter regulatory elements.
Materials and methods
All chemicals were purchased from Sigma (Castle Hill, NSW, Australia) unless otherwise indicated.
Genomic organisation of mouse Txnrd1 gene
• Cloning of mouse genomic Txnrd1 DNA
To obtain mouse genomic DNA clones for the determination of the genomic structure of the mouse Txnrd1 gene, we initially screened a mouse genomic DNA library in λ phage (Stratagene, La Jolla, CA, USA) with an αP32-dATP labelled mouse Txnrd1 cDNA fragment as a probe. Approximately 5 × 105 plaques were prehybridised in 10% w/v dextran sulphate (Astral, Gymea, NSA, Australia), 2% w/v sodium dodecyl sulphate, 0.04% w/v bovine serum albumin, 0.04% w/v polyvinyl pyrollidone (MW 40000), 0.04% w/v Ficoll and 1 M sodium chloride at 61 C for 4 hours. The probe was hybridised to the filters at 61 C for 12 hours. The filters were washed three times at 40 C in 2XSSC (0.3 M sodium chloride, 0.33 M sodium citrate) and 0.1% w/v sodium dodecyl sulphate. Successful screening of the mouse genomic DNA library produced two overlapping mouse Txnrd1 genomic clones approximately 15 kb in length.
The Txnrd1 cDNA fragment used in the probe was generated using reverse transcriptase PCR that utilised mRNA isolated from mouse liver tissue (Oligotex Direct mRNA Mini Kit, Qiagen, Victoria, Australia) as the template with oligonucleotides designed from the mouse Txnrd1 cDNA sequence . These two oligonucleotides (forward primer 5' ACATCTACGCCATTGGTGAC and reverse primer 5' TGGGGCTTAACCTCAGCAGC (Geneworks, Adelaide, Australia)) amplified a region of mouse Txnrd1 cDNA approximately 520 bp in length.
Mapping of mouse Txnrd1
One of the clones obtained from the mouse genomic library screen was extensively mapped using restriction enzyme digests and Southern blot analysis. The resulting sequences were aligned with the mouse Txnrd1 cDNA sequence  using MacVector™ software (Oxford Molecular Group) to reveal the intron/exon junctions for exons 5, 6, 9, 10, 11, 12, 13, 14 and 15.
To complete the intron/exon map of the mouse Txnrd1 gene, the mouse Txnrd1 cDNA sequence was used to BLAST-search  the NCBI Trace Archive for mouse genomic DNA fragments containing exons 1, 2, 3, 4, 7, 8 and 16. Numerous 1 kb genomic sequences were obtained and aligned with the relevant exon sequences via MacVector™ software to reveal the intron/exon junctions.
Genomic organisation of the human TXNRD1 gene
The human TXNRD1 cDNA sequence  was used to BLAST-search the NCBI human genome database for the TXNRD1 genomic DNA sequence. The resulting genomic sequence was aligned with the human TXNRD1 cDNA sequence using MacVector™ software to reveal intron/exon junctions.
Alternative splicing patterns
BLAST-searches  of the NCBI EST and Trace Archive databases were used to analyse the alternative splicing patterns in the mouse Txnrd1 gene.
BLAST-searches of the NCBI EST and human genome databases were used to analyse the alternative splicing patterns in the human TXNRD1 gene.
The human TXNRD1 promoter sequence was used to BLAST-search the NCBI Trace Archive for the potential mouse Txnrd1 promoter region.
Basic Local Alignment Search Tool
Expressed Sequence Tags
National Centre of Biotechnology Information
Polymerase Chain Reaction
We would like to thank Joe Rothnagel (University of Queensland) for assistance with the mouse genomic library. This project was supported by Griffith University and a postgraduate research scholarship awarded to Simone Osborne by the Queensland Cancer Fund.
- Holmgren A: Thioredoxin. J Biol Chem. 1985, 54: 237-271. 10.1146/annurev.biochem.54.1.237.Google Scholar
- Laurent TC, Moore EC, Reichard P: Enzymatic synthesis of deoxyribonucleotides. VI. Isolation and characterization of thioredoxin, the hydrogen donor from Escherichia coli B. J Biol Chem. 1964, 239: 3436-3444.PubMedGoogle Scholar
- Nakamura H, Nakamura K, Yodoi J: Redox regulation of cellular activation. Annu Rev Immunol. 1997, 15: 351-369. 10.1146/annurev.immunol.15.1.351.View ArticlePubMedGoogle Scholar
- Schallreuter KU, Wood JM: The role of Thioredoxin Reductase in the reduction of free radicals at the surface of the epidermis. Biochem Biophys Res Commun. 1986, 136: 630-637.View ArticlePubMedGoogle Scholar
- Gallegos A, Gasdaska J, Taylor C, Paine-Murrieta G, Goodman D, Gasdaska P, Berggren M, Briehl M, Powis G: Transfection with human thioredoxin increases cell proliferation and a dominant-negative mutant thioredoxin reverses the transformed phenotype of human breast cancer cells. Cancer Res. 1996, 56: 5765-5770.PubMedGoogle Scholar
- Luthman M, Holmgren A: Rat Liver Thioredoxin and Thioredoxin Reductase: purification and characterisation. Biochemistry. 1982, 21: 6628-6633.View ArticlePubMedGoogle Scholar
- Tamura T, Stadtman TC: A new selenoprotein from human lung adenocarcinoma cells: purification, properties and thioredoxin reductase activity. Proc Natl Acad Sci USA. 1996, 93: 1006-1011. 10.1073/pnas.93.3.1006.PubMed CentralView ArticlePubMedGoogle Scholar
- Gasdaska P, Gasdaska J, Cochran S, Powis G: Cloning and sequencing of a human thioredoxin reductase. FEBS Lett. 1995, 373: 5-9. 10.1016/0014-5793(95)01003-W.View ArticlePubMedGoogle Scholar
- Miranda-Vizuete A, Damdimopoulos AE, Pedrajas JR, Gustafsson JA, Spyrou G: Human mitochondrial thioredoxin reductase cDNA cloning, expression and genomic organization. Eur J Biochem. 1999, 261: 405-412. 10.1046/j.1432-1327.1999.00286.x.View ArticlePubMedGoogle Scholar
- Miranda-Vizuete A, Damdimopoulos A, Spyrou G: cDNA cloning, expression and chromosomal localization of the mouse mitochondrial thioredoxin reductase gene(1). Biochim Biophys Acta. 1999, 1447: 113-118. 10.1016/S0167-4781(99)00129-3.View ArticlePubMedGoogle Scholar
- Sun Q-A, Kirnarsky L, Sherman S, Gladyshev VN: Selenoprotein oxidoreductase with specificity for thioredoxin and glutathione systems. Proc Natl Acad Sci USA. 2001, 98: 3673-3678. 10.1073/pnas.051454398.PubMed CentralView ArticlePubMedGoogle Scholar
- Gasdaska P, Berggren M, Berry M, Powis G: Cloning, sequencing and functional expression of a novel human thioredoxin reductase. FEBS Lett. 1999, 442: 105-111. 10.1016/S0014-5793(98)01638-X.View ArticlePubMedGoogle Scholar
- Watabe S, Makino Y, Ogawa K, Hiroi T, Yamamoto Y, Takahashi SY: Mitochondrial thioredoxin reductase in bovine adrenal cortex its purification, properties, nucleotide/amino acid sequences, and identification of selenocysteine. Eur J Biochem. 1999, 264: 74-84. 10.1046/j.1432-1327.1999.00578.x.View ArticlePubMedGoogle Scholar
- Sun QA, Wu Y, Zappacosta F, Jeang KT, Lee BJ, Hatfield DL, Gladyshev VN: Redox regulation of cell signaling by selenocysteine in mammalian thioredoxin reductases. J Biol Chem. 1999, 274: 24522-24530. 10.1074/jbc.274.35.24522.View ArticlePubMedGoogle Scholar
- Kawai H, Ota T, Suzuki F, Tatsuka M: Molecular cloning of mouse thioredoxin reductases. Gene. 2000, 242: 321-330. 10.1016/S0378-1119(99)00498-9.View ArticlePubMedGoogle Scholar
- Gasdaska J, Gasdaska P, Gallegos A, Powis G: Human thioredoxin reductase gene localization to chromosomal position 12q23-q24.1 and mRNA distribution in human tissue. Genomics. 1996, 37: 257-259. 10.1006/geno.1996.0554.View ArticlePubMedGoogle Scholar
- Sun QA, Zappacosta F, Factor VM, Wirth PJ, Hatfield DL, Gladyshev VN: Heterogeneity within animal thioredoxin reductases. Evidence for alternative first exon splicing. J Biol Chem. 2001, 276: 3106-3114. 10.1074/jbc.M004750200.View ArticlePubMedGoogle Scholar
- Rundlof AK, Carlsten M, Arner ES: The core promoter of human thioredoxin reductase 1: cloning, transcriptional activity, and oct-1, sp1, and sp3 binding reveal a housekeeping-type promoter for the au-rich element-regulated gene. J Biol Chem. 2001, 276: 30542-30551. 10.1074/jbc.M101452200.View ArticlePubMedGoogle Scholar
- Mount SM: A catalogue of splice junction sequences. Nucleic Acids Res. 1982, 10: 459-472.PubMed CentralView ArticlePubMedGoogle Scholar
- Tonissen K, Wells J: Isolation and characterization of human thioredoxin-encoding genes. Gene. 1991, 102: 221-228. 10.1016/0378-1119(91)90081-L.View ArticlePubMedGoogle Scholar
- Matsui M, Taniguchi Y, Hirota K, Taketo M, Yodoi J: Structure of the mouse thioredoxin-encoding gene and its processed pseudogene. Gene. 1995, 152: 165-171. 10.1016/0378-1119(94)00707-Y.View ArticlePubMedGoogle Scholar
- Rundlof AK, Carlsten M, Giacobini MM, Arner ES: Prominent expression of the selenoprotein thioredoxin reductase in the medullary rays of the rat kidney and thioredoxin reductase mRNA variants differing at the 5' untranslated region. Biochem J. 2000, 347: 661-668. 10.1042/0264-6021:3470661.PubMed CentralView ArticlePubMedGoogle Scholar
- Koishi R, Kawashima I, Yoshimura C, Sugawara M, Serizawa N: Cloning and characterization of a novel oxidoreductase KDRF from a human bone marrow-derived stromal cell line KM-102. J Biol Chem. 1997, 272: 2570-2577. 10.1074/jbc.272.4.2570.View ArticlePubMedGoogle Scholar
- Gasdaska JR, Harney JW, Gasdaska PY, Powis G, Berry MJ: Regulation of Human Thioredoxin Reductase Expression Activity by 3'-Untranslated Region Selenocysteine Insertion Sequence and mRNA Instability Elements. J Biol Chem. 1999, 274: 25379-25385. 10.1074/jbc.274.36.25379.View ArticlePubMedGoogle Scholar
- Altschul SF, Madden TL, Schaffer AA, Zhang J, Zhang Z, Miller W, Lipman DJ: Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Res. 1997, 25: 3389-3402. 10.1093/nar/25.17.3389.PubMed CentralView ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.