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T Ratajczak

Publications and source records attributed to T Ratajczak.

At least 19 recordsLinked to original sources
PubMed1992

Multiple elements within the glucocorticoid regulatory unit of the rat alpha 1-acid glycoprotein gene are recognition sites for C/EBP.

Sequences between -106 and -42, located immediately downstream of the glucocorticoid response element, are essential for efficient glucocorticoid-stimulated expression of the alpha 1-acid glycoprotein (AGP) gene. We have used mobility shift assays with oligonucleotides bearing wild type and mutated sequences from segmented portions of this region to characterize the specific interaction of similar binding factors from rat liver and HTC rat hepatoma cell nuclear extracts. One of these factors, AGP nuclear factor 2 (ANF-2), appears capable of dual interaction with the homologous recognition sites, HA (-133 to -104) and HB (-81 to -72), which overlap and are located downstream of the glucocorticoid response element, respectively. Using an affinity matrix containing the HB sequence we have isolated ANF-2 from rat liver nuclear extracts. On the basis of immunological evidence rat liver ANF-2 was confirmed to be highly related and probably identical to CCAAT/enhancer-binding protein (C/EBP). Methylation protection analyses with partially purified, rat liver ANF-2 confirmed HA and HB as recognition sites for C/EBP-related factors and are consistent with the location of a third interaction site for these transactivating proteins at HX (-102 to -93). We propose that the sequences HA, HX, and HB, spanning residues -113 to -72 of the AGP promoter, might serve as recognition sites for a family of C/EBP-like nuclear factors that coordinate the glucocorticoid-mediated induction of the AGP gene.

Animals↗
PubMed1991

AGP/EBP(LAP) expressed in rat hepatoma cells interacts with multiple promoter sites and is necessary for maximal glucocorticoid induction of the rat alpha-1 acid glycoprotein gene.

Transcription of the rat alpha 1-acid glycoprotein (AGP) gene is induced by glucocorticoids. In addition to the glucocorticoid response element which maps to bases -120 to -107, sequences located between bases -106 to -42 have been shown to be necessary for hormone induction. We have previously identified multiple sites of C/EBP interaction with the AGP promoter in the region -106 to -64. In this study, we purify and identify a C/EBP family member, AGP/EBP(LAP), present in the rat hepatoma cell line HTC (JZ.1) which also binds to the C/EBP recognition sites in this region. Mutations in the recognition sites that prevent binding are analyzed, and the results suggest a positive as well as a possible inhibitory role for AGP/EBP(LAP) in the glucocorticoid induction of the gene in HTC (JZ.1) cells.

Animals↗
PubMed1990

Isolation of untransformed bovine estrogen receptor without molybdate stabilization.

A low concentration estrogen-derivatized affinity resin has been used in a rapid, single step purification of the untransformed estrogen receptor from calf uterine cytosols prepared without sodium molybdata. The procedure isolates the Mr 65,000 estrogen receptor in association with the bovine heat shock protein hsp90. Small amounts of proteolyzed receptor ranging in size from Mr 50,000 to 60,000 are also present in the purified extracts. Results from affinity chromatography of receptor cytosols either untreated or presaturated with estradiol suggest that two proteins of Mr 22,000 and 38,000 are co-purified with the untransformed receptor complex and may represent additional nonhormone-binding components of the native receptor form. Some indication of the stability of protein-protein interactions within the oligomeric complex has been derived from differential salt elution studies with heparin-sepharose and affinity gel-immobilized untransformed receptor. On size exclusion high performance liquid chromatography the untransformed complex eluted with a Stokes radius of 75 +/- 2 A (n = 18), but was shown to be sensitive to extended ultracentrifugal analysis dissociating to the receptor homodimer, sedimentation coefficient 5.3 +/- 0.3 s (n = 5). Preliminary data on urea- and heat-induced transformation of the isolated receptor to the DNA-binding state is presented.

Animals↗
PubMed1990

Interaction of bovine estrogen receptor with immobilized zinc.

The metal-binding properties of partially purified untransformed or salt-dissociated bovine estrogen receptors were studied using zinc-chelated iminodiacetic acid gels. Only the salt-dissociated 5S receptor is retained by the metal-chelated resin, and this interaction is dependent on the presence of dithiothreitol. The untransformed 9S receptor is not retained, indicating that the zinc-interacting amino acid residues may be masked by receptor-associated proteins such as 90K heat-shock protein or because of an unfavorable receptor conformation.

Animals↗
PubMed1989

The interaction site for tamoxifen aziridine with the bovine estrogen receptor.

Calf uterine estrogen receptor was covalently labeled with [3H]tamoxifen aziridine during affinity chromatography purification. After carboxymethylation, affinity labeled receptor was digested with trypsin under limit conditions and the labeled peptides were fractionated by reversed-phase high performance liquid chromatography into one major and two minor components. Sequence analysis of the dominant labeled fragment indicated the facile cleavage of label during Edman degradation but identified two peptides, both derived from the extreme carboxyl terminus of the steroid-binding domain. The 17 residues of one peptide were fully conserved in all estrogen receptors. This fragment contained five nucleophilic amino acids and was considered as the more favored interaction site for tamoxifen aziridine. A corresponding region of the glucocorticoid receptor has recently been identified as one of three major contact sites for glucocorticoids (Carlstedt-Duke, J., Strömstedt, P.-E., Persson, B., Cederlund, E., Gustafsson, J.-A., and Jörnvall, H. (1988) J. Biol. Chem. 263, 6842-6846). A comparison of amino acid physical characteristics in the hormone-binding domains of human estrogen and glucocorticoid receptors demonstrated an excellent structural correlation between the two regions and delineated elements in the estrogen receptor which may be directly involved in estradiol binding.

Amino Acid Sequence↗
PubMed1988

Chemical characterization by protein sequence analysis of the bovine estrogen receptor.

Tryptic peptides generated from bovine estrogen receptor have been fractionated and purified using microbore column high performance liquid chromatography. Sequence analysis performed on six of these peptides, derived from diverse structural regions of the receptor protein, yielded 73 unique assignments corresponding to approximately 12% of the molecule. The amino acid sequences of these peptides displayed a high degree of similarity with corresponding sequences from estrogen receptors of mammalian origin, but were only moderately conserved in receptors from non-mammalian species. The sequenced residues of one tryptic peptide, positioned in the estrogen binding domain, were fully conserved in all estrogen receptors.

Amino Acid Sequence↗
PubMed1988

Sequence analysis of the nonsteroid binding component of the calf uterine estrogen receptor.

Microbore reversed-phase high performance liquid chromatography has been utilized to fractionate and purify a number of tryptic peptides generated from the 90K nonsteroid binding component of the calf uterine estrogen receptor. Sequence analysis was performed on six peptides yielding 78 unique amino acid assignments, this corresponds to approximately 10% of the molecule. These peptides share sequence similarities with three heat shock proteins, Drosophila hsp 83 (83% homologous), yeast hsp 90 (55%) and chicken hsp 108 (32%). The amino acid composition of the protein indicates a prevalence of charged amino acid residues.

Amino Acid Sequence↗
PubMed1988

Structural characterization of the 9-10S estradiol receptor from calf uterus.

An affinity chromatography-based method has been developed for estrogen receptor isolation which requires the inclusion of sodium molybdate in purification buffers for maintaining the large 9-10S form of the receptor. The protein products obtained from affinity chromatography of calf uterine receptor extracts or from extracts presaturated with estradiol have been analyzed by gel electrophoresis under denaturing conditions. Major estrogen sensitive proteins were peptides with Mr approximately 90,000, 65,000 and 50,000. Two additional proteins (60,000 and 53,000) of lower abundance and with demonstrated estrogen sensitivity were also observed. Affinity labeling with [3H]tamoxifen aziridine identified the Mr 65,000 protein as the estrogen receptor and suggested that the Mr 60,000, 53,000 and 50,000 peptide components were derived proteolytically from this parent unit. The 90,000 mol. wt component was readily dissociated from heparin-sepharose immobilized estrogen receptor by elution with low salt buffers without molybdate. Peptide mapping experiments indicated that the 90,000 mol. wt component was not related to the Mr 65,000 and 50,000 estrogen receptors, but confirmed the smaller binding unit to be a proteolytic fragment of the 65,000 mol. wt receptor. The results suggest that the 90K protein associates non-covalently with the Mr 65,000 estrogen binding unit as a nonhormone binding component of the 9-10S receptor.

Animals↗
PubMed1978

Seasonal variations in urinary excretion of calcium and magnesium in healthy subjects and patients with renal calculus and chronic renal failure.

Renal excretion of calcium in healthy subjects and in patients with renal stones increases in the summer, as compared to the winter values. In patients with chronic renal failure calciuria shows no seasonal variations. No essential difference in the monthly excretion of magnesium in 24-hour urine has been found between healthy persons and patients with renal stones.

Adolescent↗