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1.  Cephalopod eye evolution was modulated by the acquisition of Pax-6 splicing variants 
Scientific Reports  2014;4:4256.
Previous studies have reported that the developmental processes of vertebrate eyes are controlled by four Pax-6 splicing variants, each modulating different downstream genes, whereas those of insect eyes are controlled by duplicated Pax-6 genes. Cephalopods belong to the Protostomes but possess a camera-type eye similar to those in vertebrates. We examined Pax-6 variations in the squid and found five types of Pax-6 splicing variants but no duplication of the Pax-6 gene. In the five splicing variants, the splicing patterns were produced by the combination of two additional exons to the ortholog and one jettisoned exon containing most of the Homeobox domain (HD). These five variants show spatio-temporal patterns of gene expression during development in the squid. Our study suggests that cephalopods acquired Pax-6 splicing variants independent of those in vertebrates and that these variants were similarly utilized in the development of the squid eye.
PMCID: PMC3942700  PMID: 24594543
2.  CoDP: predicting the impact of unclassified genetic variants in MSH6 by the combination of different properties of the protein 
Lynch syndrome is a hereditary cancer predisposition syndrome caused by a mutation in one of the DNA mismatch repair (MMR) genes. About 24% of the mutations identified in Lynch syndrome are missense substitutions and the frequency of missense variants in MSH6 is the highest amongst these MMR genes. Because of this high frequency, the genetic testing was not effectively used in MSH6 so far. We, therefore, developed CoDP (Combination of the Different Properties), a bioinformatics tool to predict the impact of missense variants in MSH6.
We integrated the prediction results of three methods, namely MAPP, PolyPhen-2 and SIFT. Two other structural properties, namely solvent accessibility and the change in the number of heavy atoms of amino acids in the MSH6 protein, were further combined explicitly. MSH6 germline missense variants classified by their associated clinical and molecular data were used to fit the parameters for the logistic regression model and to assess the prediction. The performance of CoDP was compared with those of other conventional tools, namely MAPP, SIFT, PolyPhen-2 and PON-MMR.
A total of 294 germline missense variants were collected from the variant databases and literature. Of them, 34 variants were available for the parameter training and the prediction performance test. We integrated the prediction results of MAPP, PolyPhen-2 and SIFT, and two other structural properties, namely solvent accessibility and the change in the number of heavy atoms of amino acids in the MSH6 protein, were further combined explicitly. Variants data classified by their associated clinical and molecular data were used to fit the parameters for the logistic regression model and to assess the prediction. The values of the positive predictive value (PPV), the negative predictive value (NPV), sensitivity, specificity and accuracy of the tools were compared on the whole data set. PPV of CoDP was 93.3% (14/15), NPV was 94.7% (18/19), specificity was 94.7% (18/19), sensitivity was 93.3% (14/15) and accuracy was 94.1% (32/34). Area under the curve of CoDP was 0.954, that of MAPP for MSH6 was 0.919, of SIFT was 0.864 and of PolyPhen-2 HumVar was 0.819. The power to distinguish between pathogenic and non-pathogenic variants of these methods was tested by Wilcoxon rank sum test (p < 8.9 × 10-6 for CoDP, p < 3.3 × 10-5 for MAPP, p < 3.1 × 10-4 for SIFT and p < 1.2 × 10-3 for PolyPhen-2 HumVar), and CoDP was shown to outperform other conventional methods.
In this paper, we provide a human curated data set for MSH6 missense variants, and CoDP, the prediction tool, which achieved better accuracy for predicting the impact of missense variants in MSH6 than any other known tools. CoDP is available at
PMCID: PMC3651391  PMID: 23621914
HNPCC; In silico; Lynch syndrome; Mismatch repair; MSH6; Unclassified variants
3.  RESOPS: A Database for Analyzing the Correspondence of RNA Editing Sites to Protein Three-Dimensional Structures 
Plant and Cell Physiology  2009;50(11):1865-1873.
Transcripts from mitochondrial and chloroplast DNA of land plants often undergo cytidine to uridine conversion-type RNA editing events. RESOPS is a newly built database that specializes in displaying RNA editing sites of land plant organelles on protein three-dimensional (3D) structures to help elucidate the mechanisms of RNA editing for gene expression regulation. RESOPS contains the following information: unedited and edited cDNA sequences with notes for the target nucleotides of RNA editing, conceptual translation from the edited cDNA sequence in pseudo-UniProt format, a list of proteins under the influence of RNA editing, multiple amino acid sequence alignments of edited proteins, the location of amino acid residues coded by codons under the influence of RNA editing in protein 3D structures and the statistics of biased distributions of the edited residues with respect to protein structures. Most of the data processing procedures are automated; hence, it is easy to keep abreast of updated genome and protein 3D structural data. In the RESOPS database, we clarified that the locations of residues switched by RNA editing are significantly biased to protein structural cores. The integration of different types of data in the database also help advance the understanding of RNA editing mechanisms. RESOPS is accessible at
PMCID: PMC2775959  PMID: 19808808
Chloroplast; Mitochondrion; Molecular evolution; Organelle genome; Protein 3D structure; RNA editing
4.  The interwinding nature of protein–protein interfaces and its implication for protein complex formation 
Bioinformatics  2009;25(23):3108-3113.
Motivation: Structural features at protein–protein interfaces can be studied to understand protein–protein interactions. It was noticed that in a dataset of 45 multimeric proteins the interface could either be described as flat against flat or protruding/interwound. In the latter, residues within one chain were surrounded by those in other chains, whereas in the former they were not.
Results: A simple method was developed that could distinguish between these two types with results that matched those made by a human annotator. Applying this automatic method to a large dataset of 888 structures, chains at interfaces were categorized as non-surrounded or surrounded. It was found that the surrounded set had a significantly lower folding tendency using a sequence based measure, than the non-surrounded set. This suggests that before complexation, surrounded chains are relatively unstable and may be involved in ‘fly-casting’. This is supported by the finding that terminal regions are overrepresented in the surrounded set.
Supplementary information: Supplementary data are available at Bioinformatics online.
PMCID: PMC2778332  PMID: 19789269
5.  Characteristics and Prediction of RNA Editing Sites in Transcripts of the Moss Takakia lepidozioides Chloroplast 
RNA editing in land plant organelles is a process primarily involving the conversion of cytidine to uridine in pre-mRNAs. The process is required for gene expression in plant organelles, because this conversion alters the encoded amino acid residues and improves the sequence identity to homologous proteins. A recent study uncovered that proteins encoded in the nuclear genome are essential for editing site recognition in chloroplasts; the mechanisms by which this recognition occurs remain unclear. To understand these mechanisms, we determined the genomic and cDNA sequences of moss Takakia lepidozioides chloroplast genes, then computationally analyzed the sequences within −30 to +10 nucleotides of RNA editing sites (neighbor sequences) likely to be recognized by trans-factors. As the T. lepidozioides chloroplast has many RNA editing sites, the analysis of these sequences provides a unique opportunity to perform statistical analyses of chloroplast RNA editing sites. We divided the 302 obtained neighbor sequences into eight groups based on sequence similarity to identify group-specific patterns. The patterns were then applied to predict novel RNA editing sites in T. lepidozioides transcripts; ∼60% of these predicted sites are true editing sites. The success of this prediction algorithm suggests that the obtained patterns are indicative of key sites recognized by trans-factors around editing sites of T. lepidozioides chloroplast genes.
PMCID: PMC2575889  PMID: 18650260
bioinformatics; chloroplast; computational biology; plant organelle; singlet and doublet propensities; Takakia lepidozioides
6.  Key Interactions in Integrin Ectodomain Responsible for Global Conformational Change Detected by Elastic Network Normal-Mode Analysis 
Biophysical Journal  2008;95(6):2895-2908.
Integrin, a membrane protein with a huge extracellular domain, participates in cell-cell and cell-extracellular-matrix interactions for metazoan. A group of integrins is known to perform a large-scale structural change when the protein is activated, but the activation mechanism and generality of the conformational change remain to be elucidated. We performed normal-mode analysis of the elastic network model on integrin αVβ3 ectodomain in the bent form and identified key residues that influenced molecular motions. Iterative normal-mode calculations demonstrated that the specific nonbonded interactions involving the key residues work as a snap to keep integrin in the bent form. The importance of the key residues for the conformational change was further verified by mutation experiments, in which integrin αIIbβ3 was used. The conservation pattern of amino acid residues among the integrin family showed that the characteristic pattern of residues seen around these key residues is found in the limited groups of integrin β-chains. This conservation pattern suggests that the molecular mechanism of the conformational change relying on the interactions found in integrin αVβ3 is unique to the limited types of integrins.
PMCID: PMC2527288  PMID: 18515366
7.  Correlation between amino acid residues converted by RNA editing and functional residues in protein three-dimensional structures in plant organelles 
BMC Plant Biology  2008;8:79.
In plant organelles, specific messenger RNAs (mRNAs) are subjected to conversion editing, a process that often converts the first or second nucleotide of a codon and hence the encoded amino acid. No systematic patterns in converted sites were found on mRNAs, and the converted sites rarely encoded residues located at the active sites of proteins. The role and origin of RNA editing in plant organelles remain to be elucidated.
Here we study the relationship between amino acid residues encoded by edited codons and the structural characteristics of these residues within proteins, e.g., in protein-protein interfaces, elements of secondary structure, or protein structural cores. We find that the residues encoded by edited codons are significantly biased toward involvement in helices and protein structural cores. RNA editing can convert codons for hydrophilic to hydrophobic amino acids. Hence, only the edited form of an mRNA can be translated into a polypeptide with helix-preferring and core-forming residues at the appropriate positions, which is often required for a protein to form a functional three-dimensional (3D) structure.
We have performed a novel analysis of the location of residues affected by RNA editing in proteins in plant organelles. This study documents that RNA editing sites are often found in positions important for 3D structure formation. Without RNA editing, protein folding will not occur properly, thus affecting gene expression. We suggest that RNA editing may have conferring evolutionary advantage by acting as a mechanism to reduce susceptibility to DNA damage by allowing the increase in GC content in DNA while maintaining RNA codons essential to encode residues required for protein folding and activity.
PMCID: PMC2488346  PMID: 18631376
8.  coliSNP database server mapping nsSNPs on protein structures 
Nucleic Acids Research  2007;36(Database issue):D409-D413.
We have developed coliSNP, a database server ( that maps non-synonymous single nucleotide polymorphisms (nsSNPs) on the three-dimensional (3D) structure of proteins. Once a week, the SNP data from the dbSNP database and the protein structure data from the Protein Data Bank (PDB) are downloaded, and the correspondence of the two data sets is automatically tabulated in the coliSNP database. Given an amino acid sequence, protein name or PDB ID, the server will immediately provide known nsSNP information, including the amino acid mutation caused by the nsSNP, the solvent accessibility, the secondary structure and the flanking residues of the mutated residue in a single page. The position of the nsSNP within the amino acid sequence and on the 3D structure of the protein can also be observed. The database provides key information with which to judge whether an observed nsSNP critically affects protein function and/or stability. As far as we know, this is the only web-based nsSNP database that automatically compiles SNP and protein information in a concise manner.
PMCID: PMC2238833  PMID: 17921498
9.  Amino acid residue doublet propensity in the protein–RNA interface and its application to RNA interface prediction 
Nucleic Acids Research  2006;34(22):6450-6460.
Protein–RNA interactions play essential roles in a number of regulatory mechanisms for gene expression such as RNA splicing, transport, translation and post-transcriptional control. As the number of available protein–RNA complex 3D structures has increased, it is now possible to statistically examine protein–RNA interactions based on 3D structures. We performed computational analyses of 86 representative protein–RNA complexes retrieved from the Protein Data Bank. Interface residue propensity, a measure of the relative importance of different amino acid residues in the RNA interface, was calculated for each amino acid residue type (residue singlet interface propensity). In addition to the residue singlet propensity, we introduce a new residue-based propensity, which gives a measure of residue pairing preferences in the RNA interface of a protein (residue doublet interface propensity). The residue doublet interface propensity contains much more information than the sum of two singlet propensities alone. The prediction of the RNA interface using the two types of propensities plus a position-specific multiple sequence profile can achieve a specificity of about 80%. The prediction method was then applied to the 3D structure of two mRNA export factors, TAP (Mex67) and UAP56 (Sub2). The prediction enables us to point out candidate RNA interfaces, part of which are consistent with previous experimental studies and may contribute to elucidation of atomic mechanisms of mRNA export.
PMCID: PMC1761430  PMID: 17130160
10.  Large-scale identification and characterization of alternative splicing variants of human gene transcripts using 56 419 completely sequenced and manually annotated full-length cDNAs 
Nucleic Acids Research  2006;34(14):3917-3928.
We report the first genome-wide identification and characterization of alternative splicing in human gene transcripts based on analysis of the full-length cDNAs. Applying both manual and computational analyses for 56 419 completely sequenced and precisely annotated full-length cDNAs selected for the H-Invitational human transcriptome annotation meetings, we identified 6877 alternative splicing genes with 18 297 different alternative splicing variants. A total of 37 670 exons were involved in these alternative splicing events. The encoded protein sequences were affected in 6005 of the 6877 genes. Notably, alternative splicing affected protein motifs in 3015 genes, subcellular localizations in 2982 genes and transmembrane domains in 1348 genes. We also identified interesting patterns of alternative splicing, in which two distinct genes seemed to be bridged, nested or having overlapping protein coding sequences (CDSs) of different reading frames (multiple CDS). In these cases, completely unrelated proteins are encoded by a single locus. Genome-wide annotations of alternative splicing, relying on full-length cDNAs, should lay firm groundwork for exploring in detail the diversification of protein function, which is mediated by the fast expanding universe of alternative splicing variants.
PMCID: PMC1557807  PMID: 16914452
11.  Coverage of whole proteome by structural genomics observed through protein homology modeling database 
We have been developing FAMSBASE, a protein homology-modeling database of whole ORFs predicted from genome sequences. The latest update of FAMSBASE (, which is based on the protein three-dimensional (3D) structures released by November 2003, contains modeled 3D structures for 368,724 open reading frames (ORFs) derived from genomes of 276 species, namely 17 archaebacterial, 130 eubacterial, 18 eukaryotic and 111 phage genomes. Those 276 genomes are predicted to have 734,193 ORFs in total and the current FAMSBASE contains protein 3D structure of approximately 50% of the ORF products. However, cases that a modeled 3D structure covers the whole part of an ORF product are rare. When portion of an ORF with 3D structure is compared in three kingdoms of life, in archaebacteria and eubacteria, approximately 60% of the ORFs have modeled 3D structures covering almost the entire amino acid sequences, however, the percentage falls to about 30% in eukaryotes. When annual differences in the number of ORFs with modeled 3D structure are calculated, the fraction of modeled 3D structures of soluble protein for archaebacteria is increased by 5%, and that for eubacteria by 7% in the last 3 years. Assuming that this rate would be maintained and that determination of 3D structures for predicted disordered regions is unattainable, whole soluble protein model structures of prokaryotes without the putative disordered regions will be in hand within 15 years. For eukaryotic proteins, they will be in hand within 25 years. The 3D structures we will have at those times are not the 3D structure of the entire proteins encoded in single ORFs, but the 3D structures of separate structural domains. Measuring or predicting spatial arrangements of structural domains in an ORF will then be a coming issue of structural genomics.
PMCID: PMC1769342  PMID: 17146617
domain duplication; domain interactions; genome; homology modeling; P-loop; structural genomics
12.  Enlarged FAMSBASE: protein 3D structure models of genome sequences for 41 species 
Nucleic Acids Research  2003;31(1):463-468.
Enlarged FAMSBASE is a relational database of comparative protein structure models for the whole genome of 41 species, presented in the GTOP database. The models are calculated by Full Automatic Modeling System (FAMS). Enlarged FAMSBASE provides a wide range of query keys, such as name of ORF (open reading frame), ORF keywords, Protein Data Bank (PDB) ID, PDB heterogen atoms and sequence similarity. Heterogen atoms in PDB include cofactors, ligands and other factors that interact with proteins, and are a good starting point for analyzing interactions between proteins and other molecules. The data may also work as a template for drug design. The present number of ORFs with protein 3D models in FAMSBASE is 183 805, and the database includes an average of three models for each ORF. FAMSBASE is available at
PMCID: PMC165564  PMID: 12520053
13.  Integrative Annotation of 21,037 Human Genes Validated by Full-Length cDNA Clones 
Imanishi, Tadashi | Itoh, Takeshi | Suzuki, Yutaka | O'Donovan, Claire | Fukuchi, Satoshi | Koyanagi, Kanako O | Barrero, Roberto A | Tamura, Takuro | Yamaguchi-Kabata, Yumi | Tanino, Motohiko | Yura, Kei | Miyazaki, Satoru | Ikeo, Kazuho | Homma, Keiichi | Kasprzyk, Arek | Nishikawa, Tetsuo | Hirakawa, Mika | Thierry-Mieg, Jean | Thierry-Mieg, Danielle | Ashurst, Jennifer | Jia, Libin | Nakao, Mitsuteru | Thomas, Michael A | Mulder, Nicola | Karavidopoulou, Youla | Jin, Lihua | Kim, Sangsoo | Yasuda, Tomohiro | Lenhard, Boris | Eveno, Eric | Suzuki, Yoshiyuki | Yamasaki, Chisato | Takeda, Jun-ichi | Gough, Craig | Hilton, Phillip | Fujii, Yasuyuki | Sakai, Hiroaki | Tanaka, Susumu | Amid, Clara | Bellgard, Matthew | de Fatima Bonaldo, Maria | Bono, Hidemasa | Bromberg, Susan K | Brookes, Anthony J | Bruford, Elspeth | Carninci, Piero | Chelala, Claude | Couillault, Christine | de Souza, Sandro J. | Debily, Marie-Anne | Devignes, Marie-Dominique | Dubchak, Inna | Endo, Toshinori | Estreicher, Anne | Eyras, Eduardo | Fukami-Kobayashi, Kaoru | R. Gopinath, Gopal | Graudens, Esther | Hahn, Yoonsoo | Han, Michael | Han, Ze-Guang | Hanada, Kousuke | Hanaoka, Hideki | Harada, Erimi | Hashimoto, Katsuyuki | Hinz, Ursula | Hirai, Momoki | Hishiki, Teruyoshi | Hopkinson, Ian | Imbeaud, Sandrine | Inoko, Hidetoshi | Kanapin, Alexander | Kaneko, Yayoi | Kasukawa, Takeya | Kelso, Janet | Kersey, Paul | Kikuno, Reiko | Kimura, Kouichi | Korn, Bernhard | Kuryshev, Vladimir | Makalowska, Izabela | Makino, Takashi | Mano, Shuhei | Mariage-Samson, Regine | Mashima, Jun | Matsuda, Hideo | Mewes, Hans-Werner | Minoshima, Shinsei | Nagai, Keiichi | Nagasaki, Hideki | Nagata, Naoki | Nigam, Rajni | Ogasawara, Osamu | Ohara, Osamu | Ohtsubo, Masafumi | Okada, Norihiro | Okido, Toshihisa | Oota, Satoshi | Ota, Motonori | Ota, Toshio | Otsuki, Tetsuji | Piatier-Tonneau, Dominique | Poustka, Annemarie | Ren, Shuang-Xi | Saitou, Naruya | Sakai, Katsunaga | Sakamoto, Shigetaka | Sakate, Ryuichi | Schupp, Ingo | Servant, Florence | Sherry, Stephen | Shiba, Rie | Shimizu, Nobuyoshi | Shimoyama, Mary | Simpson, Andrew J | Soares, Bento | Steward, Charles | Suwa, Makiko | Suzuki, Mami | Takahashi, Aiko | Tamiya, Gen | Tanaka, Hiroshi | Taylor, Todd | Terwilliger, Joseph D | Unneberg, Per | Veeramachaneni, Vamsi | Watanabe, Shinya | Wilming, Laurens | Yasuda, Norikazu | Yoo, Hyang-Sook | Stodolsky, Marvin | Makalowski, Wojciech | Go, Mitiko | Nakai, Kenta | Takagi, Toshihisa | Kanehisa, Minoru | Sakaki, Yoshiyuki | Quackenbush, John | Okazaki, Yasushi | Hayashizaki, Yoshihide | Hide, Winston | Chakraborty, Ranajit | Nishikawa, Ken | Sugawara, Hideaki | Tateno, Yoshio | Chen, Zhu | Oishi, Michio | Tonellato, Peter | Apweiler, Rolf | Okubo, Kousaku | Wagner, Lukas | Wiemann, Stefan | Strausberg, Robert L | Isogai, Takao | Auffray, Charles | Nomura, Nobuo | Gojobori, Takashi | Sugano, Sumio
PLoS Biology  2004;2(6):e162.
The human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology.
An international team has systematically validated and annotated just over 21,000 human genes using full-length cDNA, thereby providing a valuable new resource for the human genetics community
PMCID: PMC393292  PMID: 15103394
14.  Revisiting gap locations in amino acid sequence alignments and a proposal for a method to improve them by introducing solvent accessibility 
Proteins  2011;79(6):1868-1877.
In comparative modeling, the quality of amino acid sequence alignment still constitutes a major bottleneck in the generation of high quality models of protein three-dimensional (3D) structures. Substantial efforts have been made to improve alignment quality by revising the substitution matrix, introducing multiple sequences, replacing dynamic programming with hidden Markov models, and incorporating 3D structure information. Improvements in the gap penalty have not been a major focus, however, following the development of the affine gap penalty and of the secondary structure dependent gap penalty. We revisited the correlation between protein 3D structure and gap location in a large protein 3D structure data set, and found that the frequency of gap locations approximated to an exponential function of the solvent accessibility of the inserted residues. The nonlinearity of the gap frequency as a function of accessibility corresponded well to the relationship between residue mutation pattern and residue accessibility. By introducing this relationship into the gap penalty calculation for pairwise alignment between template and target amino acid sequences, we were able to obtain a sequence alignment much closer to the structural alignment. The quality of the alignments was substantially improved on a pair of sequences with identity in the “twilight zone” between 20 and 40%. The relocation of gaps by our new method made a significant improvement in comparative modeling, exemplified here by the Bacillus subtilis yitF protein. The method was implemented in a computer program, ALAdeGAP (ALignment with Accessibility dependent GAp Penalty), which is available at Proteins 2011; © 2011 Wiley-Liss, Inc.
PMCID: PMC3110861  PMID: 21465562
ALAdeGAP; amino acid sequence alignment; comparative modeling; position dependent gap penalty; solvent accessibility

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