PubMed Health⌕ Search

Biomedical subjects

T Preiss

Publications and source records attributed to T Preiss.

23 records · Page 2Linked to original sources
PubMed1994

Two independent pathways for transcription from the MMTV promoter.

The influence of progesterone receptor (PR) and glucocorticoid receptor (GR) on transcription from the mouse mammary tumour virus (MMTV) promoter was analyzed using cell-free transcription of DNA templates with a G-free cassette. Preincubation of the templates with either PR or GR stimulates the rate of transcription initiation 10-50 fold, whereas the recombinant DNA binding domain of GR is inactive. Mutations that inactivate the nuclear factor I (NFI) binding site, or NFI depletion of the nuclear extract, decrease basal transcription without influencing receptor-dependent induction. Recombinant NFI, but not its DNA-binding domain, restores efficient basal transcription of the depleted extract. Recombinant OTF1 or OTF2, but not the POU domain of OTF1, enhance MMTV transcription independently of NF1. In agreement with this finding, NFI and OTF1 do not cooperate, but rather compete for binding to the wild type MMTV promoter, though they have the potential to bind simultaneously to properly oriented sites. Our results imply the existence of two independent pathways for MMTV transcription: one initiated by NFI and the other dependent on octamer transcription factors. Only the second pathway is stimulated by steroid hormone receptors in vitro.

Base Sequence↗
PubMed1993

Identification of bovine glutamate dehydrogenase as an RNA-binding protein.

Two RNA binding activities were demonstrated in bovine liver homogenate. One binding protein was isolated by a simple ion exchange and gel filtration protocol and was shown by N-terminal protein sequence analysis to be glutamate dehydrogenase. Using identical RNA substrate and assay conditions, no detectable RNA binding was observed with equimolar amounts of other representative dehydrogenases and proteins. Furthermore, excesses of tRNA, salmon testis DNA, or each of the four homoribopolymers were unable to compete for the RNA-binding site. Total cytosolic RNA, however, successfully prevented binding of radiolabeled RNA substrate. These data are consistent with glutamate dehydrogenase containing a binding site for heteropolymeric RNA with highest affinity for an as yet undefined nucleotide consensus sequence or structure. The potential physiological relevance of these observations is discussed.

Animals↗
PubMed1993

Post-transcriptional regulation of tissue-specific isoforms. A bovine cytosolic RNA-binding protein, COLBP, associates with messenger RNA encoding the liver-form isopeptides of cytochrome c oxidase.

Regulation of the liver isopeptides of bovine cytochrome c oxidase is reported to be post-transcriptional. Extensive interspecies sequence homologies exist in the 3'-untranslated regions for transcripts encoding these liver isoforms, suggesting that these regions may be involved in mediating regulation of mRNA expression. To explore this possibility, several bovine tissue homogenates were assayed for any trans-acting factors that recognized the transcript encoding the liver isoform of subunit VIII (BCOL8). Such a protein factor (COLBP: cytochrome c oxidase L-form transcript-binding protein) was identified in liver, kidney, and lung tissue and was shown to require free sulfhydryl groups for activity. No binding activity, however, was found in muscle-type homogenates. Furthermore, this binding protein also recognized the subunit VIIa-liver transcript but was unable to associate with the mRNA encoding the heart isoform of subunit VIII. Intriguingly, the tissue-specific distribution of COLBP activity parallels the presence of the liver isopeptides in the mature oxidase complex. It is therefore suggested that COLBP may mediate the tissue-specific regulation of cytochrome c oxidase liver isoform mRNA expression.

Animals↗
PubMed1993

Expression and functional analysis of steroid receptor fragments secreted from Staphylococcus aureus.

Fragments of the DNA-binding domain of the rat glucocorticoid receptor (rGR) and the human estrogen receptor (hER) were expressed in Staphylococcus aureus as a chimeric fusion to protein A by using a modified expression vector with an artificial factor X-cleavage site. The secreted product was isolated by hydrophobic chromatography on Phenyl-Sepharose and purified on DNA-cellulose or by anion-exchange chromatography. After cleavage of the protein A moiety, the purified rGR DNA-binding domain from amino acids 406 to 523 (rGR406-523), binds specifically to a glucocorticoid responsive element as a homodimer but cannot form heterodimers with the DNA-binding domain of the hER. Amino acids 510 to 523 following the zinc finger region, as well as free sulfhydryl-groups are necessary for DNA-binding, which is more efficient when the tripeptide Gly-Gly-Cys is added to the carboxy terminal end. Despite its specific interaction with DNA, rGR406-523 does not activate transcription from the MMTV promoter in a cell-free system that efficiently responds to addition of native GR, suggesting that regions essential for transcriptional activation in vitro are located outside of the DNA-binding domain.

Amino Acid Sequence↗