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C Seiser

Publications and source records attributed to C Seiser.

26 records · Page 2Linked to original sources
PubMed1992

Expression of active iron regulatory factor from a full-length human cDNA by in vitro transcription/translation.

Iron regulatory factor (IRF), also called iron responsive element-binding protein (IRE-BP), is a cytoplasmic RNA-binding protein which regulates post-transcriptionally transferrin receptor mRNA stability and ferritin mRNA translation. By using the polymerase chain reaction (PCR) and the sequence published by Rouault et al. (1990) a probe was derived which permitted the isolation of three human IRF cDNA clones. Hybridization to genomic DNA and mRNA, as well as sequencing data indicated a single copy gene of about 40 kb specifying a 4.0 kb mRNA that translates into a protein of 98,400 dalton. By in vitro transcription of a assembled IRF cDNA coupled to in vitro translation in a wheat germ extract, we obtained full sized IRF that bound specifically to a human ferritin IRE. In vitro translated IRF retained sensitivity to sulfhydryl oxidation by diamide and could be reactivated by beta-mercaptoethanol in the same way as native placental IRF. An IRF deletion mutant shortened by 132 amino acids at the COOH-terminus was no longer able to bind to an IRE, indicating that this region of the protein plays a role in RNA recognition. Placental IRF has previously been shown to migrate as a doublet on SDS-polyacrylamide gels. After V8 protease digestion the heterogeneity was located in a 65/70 kDa NH2-terminal doublet. The liberated 31 kDa COOH-terminal polypeptide was found to be homogeneous by amino acid sequencing supporting the conclusion of a single IRF gene.

Amino Acid Sequence↗
PubMed1990

The processed pseudogene of mouse thymidine kinase is active after transfection.

Aside of the gene coding for cytoplasmic thymidine kinase, the genome of mouse cells carries two pseudogenes. Both are inactive in situ. One of the pseudogenes is a processed pseudogene in which a two base pair deletion caused a shift of the reading frame and a shortening of the gene product from the 233 amino acids of thymidine kinase to 177 amino acids in the pseudogene product. We report here that introduction of this pseudogene into LTK- cells gave rise to cells with a thymidine kinase positive phenotype. The transformed cells carried multiple copies of the pseudogene the upstream region of which exhibited low but measurable promoter activity. Replacement of the upstream region of the pseudogene by a promoter of Simian virus 40 or of the mammary tumor virus resulted in high transfection efficiencies and in cell lines exhibiting high thymidine kinase activities.

Animals↗
PubMed1989

Mouse thymidine kinase: the promoter sequence and the gene and pseudogene structures in normal cells and in thymidine kinase deficient mutants.

The mouse genome carries one gene and two pseudogenes for cytoplasmic thymidine kinase. The overall structure of these genes was determined with the help of cosmids and lambda phage clones and the upstream sequence containing the promoter was determined. The data allow an allocation of bands seen in the complex patterns of genomic Southern blots obtained from the DNA of wild type cells and of thymidine kinase deficient mutants to the gene as well as to the two pseudogenes. The much used LTK cell line was found to lack the entire gene but to retain the pseudogenes. Two other TK cell lines had DNA patterns indistinguishable from the wild type. Whereas the LTK line did not produce any TKmRNA, the two other mutants had normal amounts of TKmRNA but no cytoplasmic TK activity.

Animals↗
PubMed1988

Physical map and protein gene map of cyanelle DNA from the second known isolate of Cyanophora paradoxa (Kies-strain).

A restriction map of the cyanelle DNA from a different isolate of Cyanophora paradoxa (Kies-strain) was established. The positions of 18 protein genes and the rRNA genes have been located and compared to the positions of these genes from the first isolate of C. paradoxa (Pringsheim-strain). The gene arrangement is absolutely conserved in both cyanelle DNAs. The differences in size (ca. 9 kb) and the unrelatedness in the restriction patterns could be explained by numerous small insertions into intergenic regions of the cyanelle chromosomes.

Cyanobacteria↗
PubMed1987

Cell cycle regulated synthesis of stable mouse thymidine kinase mRNA is mediated by a sequence within the cDNA.

The cDNA for mouse thymidine kinase (TK) was isolated from a cDNA library in lambda-gt11 and sequenced. It was used as a probe to follow the time course of TK mRNA expression in growth stimulated mouse fibroblasts. Linked to the HSV-TK promoter the cDNA was able to transform LTK-cells to the TK+ phenotype. The transformed cells expressed the TK mRNA and enzyme activity in a growth dependent fashion suggesting that the regulatory element is localized on the cDNA.

Animals↗