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A W Steggles

Publications and source records attributed to A W Steggles.

65 records · Page 4Linked to original sources
PubMed1971

Soluble complexes between steroid hormones and target-tissue receptors bind specifically to target-tissue chromatin.

Cytoplasmic fractions containing steroid hormone receptor were prepared from rat prostate and uterine tissues, incubated first with [(3)H]dihydrotestosterone or [(3)H]estradiol, and then with their respective target and non-target tissue chromatins. Only prostate and testis chromatin bound the dihydrotestosterone-receptor complex from prostate cytosol extensively. Similarly, uterine chromatin bound more estradiol-receptor complex from uterus than did liver, spleen, or lung chromatin. Complexes between dihydrotestosterone or estradiol with cytosols prepared from liver and spleen bound less extensively, and similarly, to all chromatins. Analogous results are described for the [(3)H]progesterone-receptor complex from chick oviduct cytosol binding to oviduct chromatin. These studies suggest that the chromatin of all steroid hormone target tissues may contain "acceptor sites" for their respective hormone-receptor complexes, and are thus programmed to receive the complex as it is transferred into the nucleus from the cytoplasm of the cell.

Animals↗
PubMed1970

The use of protamine to study [6,7-3H] oestradiol-17-beta binding in rat uterus.

1. The binding of [6,7-(3)H]oestradiol-17beta to uteri has been studied by using sucrose-gradient analysis and also the property of oestradiol receptors to form insoluble complexes with protamine. 2. Protamine precipitates the 8S and part of the 4S oestradiol-binding proteins in uterine cytoplasm from mature rats. It does not precipitate the oestradiol-17beta-binding proteins present in cytoplasm from non-target tissues or serum. No tritium-labelled material was precipitated by protamine after equilibration of [6,7-(3)H]oestradiol-17beta with either serum albumin or phosvitin. 3. Protamine precipitated a small amount of progesterone but not testosterone or cortisol that had been equilibrated with uterine cytoplasm. It did not precipitate any tritium radioactivity from muscle cytoplasm that had been equilibrated with either [1,2-(3)H]testosterone sulphate or [1,2-(3)H]dehydroepiandrosterone. 4. A simple method has been devised for measuring binding constants of tissue extracts for [6,7-(3)H]oestradiol-17beta, based on precipitation with protamine. Reasonable agreement was obtained between the values obtained by this method and those obtained by sucrose-gradient analysis. 5. This method has been used to study the effect of maturity, ovariectomy, adrenalectomy and hypophysectomy on the cytoplasmic binding of [6,7-(3)H]oestradiol-17beta. None of these procedures affected the dissociation constant K(d) or the number of binding sites/mg of cytoplasmic protein. When measured per uterus or per mg of DNA, ovariectomy and hypophysectomy decreased the number of binding sites. Adrenalectomy had no effect. 6. The properties of the 4S oestradiol-binding protein present in cytoplasm from mature uteri have been studied. It is not present in uteri from immature, ovariectomized, or hypophysectomized rats and it does not bind testosterone or cortisol. Unlabelled oestradiol-17beta, U-11,100A, N-ethylmaleimide and N-bromosuccinimide all decrease the binding of [6,7-(3)H]oestradiol-17beta to both 8S and 4S receptors. Binding to both 8S and 4S receptors decreases when oestradiol is transported to the nucleus. The 4S receptor is not the same as the 4S binding component formed by salt dissociation of the 8S receptor.

Adrenal Glands↗
PubMed1969

The properties of a nuclear acidic protein fraction that binds [6,7-3H]oestradiol-17beta.

1. Additional evidence was obtained that the nuclear oestradiol-17beta receptor is an acidic protein. Partial purification of the receptor protein was obtained by chromatography on hydroxyapatite and it contains protein-bound phosphate. 2. The nuclear ;5s' and cytoplasmic ;9.5s' and ;5s' receptors from uterus, dimethylbenzanthracene-induced mammary adenocarcinoma and kidney are precipitated together with bound oestradiol-17beta by protamine sulphate. This common property suggests that the nuclear and cytoplasmic receptors are related to each other. 3. The properties of two acidic protein fractions from both liver and dimethylbenzanthracene-induced mammary adenocarcinoma are described. Fraction 1 contains two major components and fraction 2 contains one component, as judged from polyacrylamide-gel electrophoresis. Fraction 2 contains RNA and both fractions contain protein-bound phosphate. 4. These fractions form insoluble complexes with calf thymus histone, protamine sulphate and poly-l-lysine. The formation of these complexes is markedly affected by ionic strength and pH. Ionization of both the in-amino group of lysine and carboxyl group are involved. RNA and DNA do not appear to be involved. The interaction is not affected by EDTA or 1mm-Na(+), -K(+), -Ca(2+), -Mg(2+) or -Mn(2+). Per unit weight, whole histone has 4-5 times as many binding sites for the acidic proteins as the latter have for the former. 5. No convincing evidence was obtained for DNA-acidic protein interaction, but, as judged from precipitation experiments, there was competition between DNA and acidic protein for histone. 6. Relatively large amounts of acidic protein partly relieved the histone inhibition of the template activity of DNA for Escherichia coli RNA polymerase (EC 2.7.7.6).

Adenocarcinoma↗
PubMedDate not supplied

Cholecystokinin receptor binding levels in the genetically obese rat brain.

Cholecystokinin (CCK) receptor binding levels were compared between groups of genetically obese (fa/fa) and non-obese (Fa/-) Zucker rats of both sexes. The radioligand used was the iodinated octapeptide (CCK-8). Binding was measured in eight brain regions. The relative distribution among different brain regions of specifically bound CCK per mg protein was similar in all groups of animals. High binding levels were present in the olfactory bulb, cortex and caudate nucleus. Moderate levels were seen in hippocampus and hypothalamus, and low levels were observed in hindbrain, midbrain and thalamus. Obese animals of both sexes had significantly higher CCK receptor binding levels in the hippocampus and in the midbrain in comparison to lean controls. The male obese animals also had significantly elevated binding levels in the thalamic sample. These results demonstrate a correlation between genetic obesity and elevated CCK receptor binding levels in specific brain regions.

Animals↗