Biomedical subjects

I Liebich

Publications and source records attributed to I Liebich.

12 recordsLinked to original sources

PubMed2006

TRANSFAC and its module TRANSCompel: transcriptional gene regulation in eukaryotes.

The TRANSFAC database on transcription factors, their binding sites, nucleotide distribution matrices and regulated genes as well as the complementing database TRANSCompel on composite elements have been further enhanced on various levels. A new web interface with different search options and integrated versions of Match and Patch provides increased functionality for TRANSFAC. The list of databases which are linked to the common GENE table of TRANSFAC and TRANSCompel has been extended by: Ensembl, UniGene, EntrezGene, HumanPSD and TRANSPRO. Standard gene names from HGNC, MGI and RGD, are included for human, mouse and rat genes, respectively. With the help of InterProScan, Pfam, SMART and PROSITE domains are assigned automatically to the protein sequences of the transcription factors. TRANSCompel contains now, in addition to the COMPEL table, a separate table for detailed information on the experimental EVIDENCE on which the composite elements are based. Finally, for TRANSFAC, in respect of data growth, in particular the gain of Drosophila transcription factor binding sites (by courtesy of the Drosophila DNase I footprint database) and of Arabidopsis factors (by courtesy of DATF, Database of Arabidopsis Transcription Factors) has to be stressed. The here described public releases, TRANSFAC 7.0 and TRANSCompel 7.0, are accessible under http://www.gene-regulation.com/pub/databases.html.

Animals↗

PubMed2004

The Helmholtz Network for Bioinformatics: an integrative web portal for bioinformatics resources.

SUMMARY: The Helmholtz Network for Bioinformatics (HNB) is a joint venture of eleven German bioinformatics research groups that offers convenient access to numerous bioinformatics resources through a single web portal. The 'Guided Solution Finder' which is available through the HNB portal helps users to locate the appropriate resources to answer their queries by employing a detailed, tree-like questionnaire. Furthermore, automated complex tool cascades ('tasks'), involving resources located on different servers, have been implemented, allowing users to perform comprehensive data analyses without the requirement of further manual intervention for data transfer and re-formatting. Currently, automated cascades for the analysis of regulatory DNA segments as well as for the prediction of protein functional properties are provided. AVAILABILITY: The HNB portal is available at http://www.hnbioinfo.de

Algorithms↗

PubMed2002

Evaluation of sequence motifs found in scaffold/matrix-attached regions (S/MARs).

Based on the contents of the database S/MARt DB, the most comprehensive data collection of scaffold/matrix-attached regions (S/MARs) publicly available thus far, we initiated a systematic evaluation of the stored data. By analyzing the 245 S/MAR sequences presently described in this database, we found that the S/MARs contained in this collection are generally AT-rich, with certain significant exceptions. Comparative analyses showed that most of the AT-rich motifs which were found to be enriched in S/MARs are also enriched in randomized S/MAR sequences of the same AT content. Some sequence patterns previously suggested to be characteristic for S/MARs were also investigated, among them potential binding sites for homeodomain transcription factors. Even though hexanucleotides containing the core motif of homeodomain factors were frequently observed in S/MARs, only a few potential binding sites for these factors were found enriched when compared with regulatory regions or exon sequences. All our analyses indicated that, on average, the observed frequency of motifs in S/MAR elements is largely influenced by the AT content. Our results can serve as a guideline for further improvements in the definition of S/MARs, which are now believed to constitute the functional coordinate system for genomic regulatory regions.

AT Rich Sequence↗

PubMed2001

The TRANSFAC system on gene expression regulation.

The TRANSFAC database on transcription factors and their DNA-binding sites and profiles (http://www.gene-regulation.de/) has been quantitatively extended and supplemented by a number of modules. These modules give information about pathologically relevant mutations in regulatory regions and transcription factor genes (PathoDB), scaffold/matrix attached regions (S/MARt DB), signal transduction (TRANSPATH) and gene expression sources (CYTOMER). Altogether, these distinct database modules constitute the TRANSFAC system. They are accompanied by a number of program routines for identifying potential transcription factor binding sites or for localizing individual components in the regulatory network of a cell.

Binding Sites↗

PubMed2001

Subcellular distribution of 14-3-3 proteins in the unicellular green alga Chlamydomonas reinhardtii.

A polyclonal antibody was raised against a recombinant Chlamydomonas 14-3-3-beta-galactosidase (beta-Gal) fusion protein and characterized for its epitope specificity towards the corresponding Chlamydomonas 14-3-3 protein by scan-peptide analysis. This antibody recognized four Chlamydomonas polypeptides with apparent molecular masses 32, 30, 27, and 24 kDa, which also reacted with the antiserum depleted of anti-(Escherichia coli beta-Gal) IgG, but not with the corresponding preimmune serum or the antiserum preincubated with purified 14-3-3 proteins. Western-blot analyses performed with the antibody depleted of anti-(beta-Gal) IgG revealed that more or less pronounced levels of 14-3-3 proteins were present in all subcellular fractions of Chlamydomonas reinhardtii except the nuclei. The highest levels of 14-3-3 protein were observed in the cytosol and microsomal fraction. The 30-kDa isoform was predominant in the cytosol, whereas the 27-kDa isoform was prevalent in the microsomes. When microsomal membranes were separated by sucrose-density-gradient centrifugation, Western-blot analysis revealed distinct patterns of 14-3-3 isoforms in the endoplasmic reticulum, dictyosome, and plasma membrane fractions identified by marker enzyme activities. These findings indicate that the four 14-3-3 proteins of C. reinhardtii differentially interact with endoplasmic reticulum, dictyosomes, and plasma membrane.

14-3-3 Proteins↗

PubMed2000

Nucleotide sequence, genomic organization and cell-cycle-dependent expression of a Chlamydomonas 14-3-3 gene.

Members of the 14-3-3 protein family have been identified as regulatory elements in intracellular signalling pathways and cell cycle control. Previously we reported the nucleotide sequence of a 14-3-3 cDNA cloned from the unicellular green alga Chlamydomonas reinhardtii. In this communication, we describe the nucleotide sequence, the genomic organization and the cell-cycle-dependent expression of the corresponding gene. The coding sequence of this gene was found to be interrupted by four introns of 124, 116, 81, and 659 bp, respectively. Introns 2-4 were found in conserved positions as compared to the Arabidopsis 14-3-3 genes. A counterpart to intron 1 absent in the Arabidopsis 14-3-3 genes was found in the human 14-3-3 epsilon gene.

14-3-3 Proteins↗

PubMed2000

TRANSFAC: an integrated system for gene expression regulation.

TRANSFAC is a database on transcription factors, their genomic binding sites and DNA-binding profiles (http://transfac.gbf.de/TRANSFAC/). Its content has been enhanced, in particular by information about training sequences used for the construction of nucleotide matrices as well as by data on plant sites and factors. Moreover, TRANSFAC has been extended by two new modules: PathoDB provides data on pathologically relevant mutations in regulatory regions and transcription factor genes, whereas S/MARt DB compiles features of scaffold/matrix attached regions (S/MARs) and the proteins binding to them. Additionally, the databases TRANSPATH, about signal transduction, and CYTOMER, about organs and cell types, have been extended and are increasingly integrated with the TRANSFAC data sources.

Database Management Systems↗

PubMed1999

Expanding the TRANSFAC database towards an expert system of regulatory molecular mechanisms.

TRANSFAC is a database on transcription factors, their genomic binding sites and DNA-binding profiles. In addition to being updated and extended by new features, it has been complemented now by a series of additional database modules. Among them, modules which provide data about signal transduction pathways (TRANSPATH) or about cell types/organs/developmental stages (CYTOMER) are available as well as an updated version of the previously described COMPEL database. The databases are available on the WWW at http://transfac.gbf.de/

Animals↗

PubMed1996

Immunological identification of a putative precursor of the insoluble glycoprotein framework of the Chlamydomonas cell wall.

To identify precursors of the insoluble glycoprotein framework of the Chlamydomonas cell wall, a polyclonal antibody was raised against the mixture of polypeptides released from the insoluble wall fraction by chemical deglycosylation. This antibody preferentially cross-reacted with a '150 kDa' salt-soluble cell wall glycoprotein. The conclusion that this '150 kDa' glycoprotein is a putative precursor of the insoluble cell wall fraction was corroborated by the results of pulse-chase experiments and by experiments with antibodies raised against the '150 kDa' salt-soluble glycoprotein and against its 100 kDa deglycosylation product, respectively. Whereas the antibody against the '150 kDa' glycoprotein preferentially recognized carbohydrate side chains, the antibody against its 100 kDa deglycosylation product was found to have essentially the same specificity towards glycosylated and deglycosylated cell wall components as the antibody against the deglycosylation products of the insoluble wall fraction. Furthermore, the antibody against the deglycosylated, insoluble wall fraction recognized almost the same set of peptide fragments derived by V8 protease treatment from the '150 kDa' salt-soluble cell wall glycoprotein and its 100 kDa deglycosylation product, respectively, as the antibody against the 100 kDa deglycosylated cell wall polypeptide.

Amino Acid Sequence↗

PubMed1995

A Chlamydomonas homologue to the 14-3-3 proteins: cDNA and deduced amino acid sequence.

We have isolated and sequenced a 1464 bp cDNA from the unicellular green alga Chlamydomonas reinhardtii encoding an acidic polypeptide (259 aa) with considerable homologies to the 14-3-3 proteins of animals, yeasts and higher plants. Like the other members of this highly conserved protein kinase regulatory protein family, the deduced amino acid sequence of the Chlamydomonas 14-3-3 protein includes two putative phosphorylation sites within the N-terminal region (positions 62 and 67). Furthermore, an EF hand motif characteristic for Ca(2+)-binding sites is located within the C-terminal part of this polypeptide (positions 208-219). EF hand motifs are also present in the 14-3-3 proteins of some higher plants but not in those of animals and yeasts.

14-3-3 Proteins↗

PubMed1994

Two genes encoding ribosomal protein L3 of Schizosaccharomyces pombe and their proximal promoter regions.

We have cloned and sequenced two genes, rpl3-1 and rpl3-2, encoding the ribosomal protein L3 of Schizosaccharomyces pombe. The two genes contain an open reading frame encoding 388 amino acids (aa) with a M(r) of 43,808. The aa sequences are identical, except at position 78, where Rpl3-1 displays a valine residue and Rpl3-2 contains isoleucine. The aa sequences show 75% identity to the RPL3 aa sequence from Saccharomyces cerevisiae. S1-nuclease protection analysis revealed that both genes are transcribed. The promoter sequences of the two rpl3 genes are significantly different, but both promoters contain the conserved homol-D element. Transcription starts between 40 and 50 nt downstream from this element.

Amino Acid Sequence↗

PubMed1992

Transoesophageal stress echocardiography for pre-operative detection of patients at risk of intra-operative myocardial ischaemia.

Patients with coronary artery disease have an increased risk of developing intra-operative myocardial ischaemia and peri-operative myocardial infarction. Pre-operative identification of patients at risk of developing peri-operative myocardial ischaemia is often difficult or even impossible due to the inability of the patient to perform an exercise test. For those unable to perform physical exercise a system has recently been described combining transoesophageal echocardiography with simultaneous transoesophageal atrial pacing via the same probe to detect pacing-induced wall motion abnormalities, a sign of coronary artery disease. In a prospective study, 20 patients with clinically suspected coronary artery disease undergoing hip replacement were examined pre-operatively by transoesophageal stress echocardiography. During the subsequent operation the incidence of intra-operative ischaemia was evaluated again in all 20 patients by transoesophageal echocardiography. In eight of the 20 patients (40%) wall motion abnormalities could be induced by transoesophageal stress echocardiography pre-operatively. Intra-operative wall motion abnormalities occurred in six of these eight patients. In two patients with wall motion abnormalities induced by transoesophageal stress echocardiography no abnormalities occurred during surgery. However, in those in whom wall motion abnormalities did occur during operation they occurred in the same left ventricular segment as those initiated by stress echocardiography. None of the patients without pre-operatively inducible wall motion abnormality developed them during surgery. No patient developed a myocardial infarction intra- or post-operatively. Thus, preoperative transoesophageal stress echocardiography is a valuable technique for the detection of patients who may develop ischaemic wall motion abnormalities during surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗