Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binding sites for prolactin were identified in a plasma-membrane-enriched fraction isolated from livers of mature female rats. 125I-labelled sheep prolactin prepared by the lactoperoxidase procedure retained the same molecular integrity and binding affinity as the native hormone at physiological pH. The receptors bound prolactin from different species, whereas non-lactogenic hormones were not bound. The binding of 125I-labelled sheep prolactin was activated equally by bivalent and univalent cations, bivalent cations exerting their maximal effect at much lower concentrations. The association of 125I-labelled sheep prolactin with the receptor was a time- and temperature-dependent process. Partial dissociation was detected. The binding of 125I-labelled sheep prolactin was strongly influenced by pH, with an optimum observed at pH 6.5. Receptor activity was destroyed by Pronase and phospholipase C, whereas neuraminidase increased binding. Treatment of the membranes by ribonuclease and deoxyribonuclease did not affect the binding. Binding of 125I-labelled sheep prolactin was inhibited by p-chloromercuribenzoic acid, dithiothreitol and by brief exposure to high temperatures. Scatchard analysis of the binding of 125I-labelled sheep prolactin to receptors indicated that prolactin has a high affinity for its receptor. Binding of prolactin to liver membranes showed some properties different from those observed with mammary cells. Binding by these tissues differed in pH optimum, in effects of ions, and in response to neuraminidase.
...
PMID:Characterization of prolactin binding by membrane preparations from rat liver. 3 84

Using the cDNA coding for the human interferon alpha/beta receptor (IFNAR), the IFNAR gene has been physically mapped relative to the other loci of the chromosome 21q22.1 region. 32,906 base pairs covering the IFNAR gene have been cloned and sequenced. Primer extension and solution hybridization-ribonuclease protection have been used to determine that the transcription of the gene is initiated in a broad region of 20 base pairs. Some aspects of the polymorphism of the gene, including noncoding sequences, have been analyzed; some are allelic differences in the coding sequence that induce amino acid variations in the resulting protein. The exon structure of the IFNAR gene and of that of the available genes for the receptors of the cytokine/growth hormone/prolactin/interferon receptor family have been compared with the predictions for the secondary structure of those receptors. From this analysis, we postulate a common origin and propose an hypothesis for the divergence from the immunoglobulin superfamily.
...
PMID:The structure of the human interferon alpha/beta receptor gene. 137 Aug 33

Native disulphide-bonded prolactin (band III) was distinguished from reduced prolactin (band II) and intermediate unstable disulphide-linked conformations by: (a) faster mobility of the former in sodium dodecyl sulphate/polyacrylamide gel electrophoresis, and (b) high-pressure liquid chromatography analyses of tryptic-digested peptides derived from prolactin in various conformations during its refolding pathway from reduced, unfolded to native conformation. The electrophoretic separation has been used to examine the state of disulphide bonding in newly synthesised prolactin translated from bovine pituitary mRNA in a rabbit reticulocyte translation system supplemented with nuclease-treated dog pancreatic microsomal membranes. The formation of correct disulphide pairing in prolactin (band III), synthesised in the in vitro translation system in the presence of pancreatic microsomes, required the presence of a thiol oxidant such as oxidised glutathione during the translation. The action of thiol oxidants on the in vitro biosynthesised and microsomally processed prolactin were both dose-dependent and catalytic; non-thiol oxidants such as NAD+ and NADP+ were ineffective. Examination of the time course of addition of oxidised glutathione to translating lysates showed that efficient and correct disulphide pairing in newly biosynthesised prolactin occurred when the oxidant was present co-translationally, but much lower yields of correctly disulphide-bonded prolactin were obtained when the oxidant was added after translation and processing were complete. The presence of protein-disulphide isomerase in dog pancreatic microsomes, employed in the in vitro translation system to process preprolactin, was demonstrated by (a) two-dimensional polyacrylamide gel electrophoresis of the membrane proteins, and (b) enzymic activity to accelerate reactivation of scrambled ribonuclease. Protein-disulphide isomerase activity was latent in intact microsomal vesicles, full activity being expressed upon sonication. A procedure has been devised to prepare pancreatic microsomal vesicles depleted of protein-disulphide isomerase which are active in processing and segregating in vitro biosynthesised prolactin. These membranes in the presence of low concentrations of oxidised glutathione are less active but in the presence of saturating levels of oxidised glutathione are fully competent in forming correct disulphide bridges in newly synthesised prolactin.
...
PMID:Studies on the formation of intrachain disulphide bonds in newly biosynthesised bovine prolactin. Role of protein-disulphide isomerase. 406 47

Epithelial tubulogenesis is responsible for the exquisitely intricate organization of functional units of parenchymal organs. We have previously demonstrated that hepatocyte growth factor (HGF--also known as scatter factor) is a stroma-derived epithelial morphogen, which induces tubulogenesis by kidney-derived epithelial cells in vitro. The mammary gland provides a particularly attractive model for the study of epithelial morphogenesis, since its development in postnatal life involves elongation and branching of epithelial tubules. The aim of the present studies was to assess the expression and modulation of HGF and its receptor c-Met in the rat mammary gland during pregnancy, lactation, and involution. By ribonuclease protection assay, we demonstrate that levels of both HGF and c-met transcripts are progressively reduced during pregnancy, are virtually undetectable during lactation, and increase during the phase of involution to prepregnancy levels. The reduction in HGF and c-met expression corresponds to periods in which functions other than tubulogenesis predominate in the mammary gland, namely alveologenesis (mid to late pregnancy) and milk protein synthesis (lactation). Using a murine mammary gland-derived epithelial cell line, we demonstrate that levels of c-met mRNA are significantly reduced by exogenously added prolactin, providing a possible explanation for the reduction in c-met in the rat mammary gland during lactation. The potential significance of down-regulation of HGF/c-met during lactation is discussed.
...
PMID:Modulation of hepatocyte growth factor and c-met in the rat mammary gland during pregnancy, lactation, and involution. 762 35

The effect of prolactin on the digestive potency of the acinar pancreas was examined in pituitary-grafted hyperprolactinemic mice, because our previous experiment showed that a marked proliferation of pancreatic acinar cells was induced by pituitary grafting in mice. To know whether the digestive function is modified, the tissue contents of pancreatic digestive enzymes, such as chymotrypsin, lipase alpha-amylase and ribonuclease, were measured in the hyperprolactinemic mice. Pituitary grafting significantly increased the contents of chymotrypsin and lipase in the pancreas on day 12 after the operation without affecting intake of food, when compared to those in the sham-operated controls. On day 30, however, the differences between pituitary-grafted and control mice were no more discernible. Thus, the digestive enzyme activities are easily modified soon after the increase of circulating prolactin level. This effect of prolactin on the function of the pancreas may be responsible for "homeorhetic" control of nutrients during lactation. In another set of experiments in adrenalectomized-castrated or castrated mice, pituitary grafting induced an increase in the weight of the pancreas. In addition, adrenalectomy in combination with castration did not alter the pancreatic contents of chymotrypsin and lipase but decreased the amylase content. These results taken together seem to indicate that the effect of prolactin on the exocrine pancreas is not mediated by gonadal and adrenal steroid hormones.
...
PMID:Modification of pancreatic digestive function by pituitary grafting in mice. 765 48

There have been many reports on radioisotopic in situ hybridization (ISH) studies for the demonstration of pituitary hormone mRNAs in normal pituitary gland and pituitary adenomas. Recent studies have revealed that non-radioisotopic ISH has several advantages over the radioisotopic method. Using ISH with biotinylated oligonucleotide probes, we have been able to localize various pituitary hormone mRNAs in paraffin wax or frozen sections of rat normal pituitary gland and human pituitary adenomas. For control studies we used ISH with sense probes, ISH without probes, pretreatment with ribonuclease, ISH with a probe for beta-actin and Northern blot hybridization. Using biotinylated probes, gene transcripts of rat growth hormone and prolactin were detected by Northern blot hybridization. The same biotinylated probes were used not for light microscope ISH but also for the electron microscopical demonstration of rat growth hormone and prolactin mRNAs on the polysomes of the rough endoplasmic reticula. It is emphasized that biotinylated oligonucleotide probes are useful for the analysis of pituitary endocrine function because they are applicable to the three hybridization methods, namely, Northern blot hybridization and ISH at the light and electron microscope levels.
...
PMID:Application of biotinylated oligonucleotide probes to the detection of pituitary hormone mRNA using northern blot analysis, in situ hybridization at the light- and electron-microscope levels. 788 87

Experiments were designed to examine whether vasoactive intestinal polypeptide (VIP), a known stimulator of basal prolactin (PRL) secretion, regulates PRL gene expression in the rat diethylstilbestrol (DES)-induced prolactinoma model. The VIP-induced increase in PRL release could result from increased PRL synthesis and/or decreased PRL degradation. Male Fischer 344 rats were implanted with 10 mg DES pellets 40 or 110 days prior to obtaining the anterior pituitary glands for cell dispersal. Cells were incubated in 1:10 normal rabbit serum or VIP antiserum (AVIP). After incubation, cells were pelleted, washed, and pooled for total nucleic acid extraction. The rat PRL (rPRL) mRNA abundance was quantitated using a solution hybridization/ribonuclease protection assay. Supernatant was collected and analyzed for PRL content using radioimmunoassay. Results from this experiment reveal partial immunoneutralization of intrapituitary VIP significantly decreased PRL secretory rate by rapid reduction in rRPL mRNA in the 40-day tumors. However, in the 110-day tumors the rPRL mRNA steady-state levels were unchanged but the basal release of PRL continued to be decreased by AVIP. These results indicate VIP exerts its effects on PRL secretion through at least two mechanisms.
...
PMID:Vasoactive intestinal polypeptide antiserum affects rat prolactin mRNA in 40-day but not 110-day diethylstilbestrol-induced prolactinoma tissue. 803 86

As a first step towards the development of a sensitive ribonuclease protection assay to study the regulation of somatolactin (SL) mRNA expression in pituitary cells of goldfish, we have isolated a complementary DNA (cDNA) clone encoding precursor sequence of SL from a cDNA library prepared from goldfish pituitary poly(A)+ RNA. The 843-bp goldfish SL (gfSL) cDNA has an open reading frame of 693 nucleotides with two possible start codons of AUG. Amino acid sequence alignment revealed that gfSL has the characteristics of four conserved domains (A, B, C and D) common to all SLs with the domain B being the most conserved region among all the characterized SLs. Similar to other teleost SLs, this gfSL is similarly related but clearly distinct from growth hormone and prolactin of goldfish and other teleosts. However, unlike most other known teleost SLs which have more than 70% amino acid sequence identity to each other, the overall amino acid sequence identity of this novel gfSL with other previously characterized SLs ranges from only 36% to 51%. Moreover, this gfSL contains only six cysteine residues, rather than seven in most other SLs, in conserved positions. Northern blot analysis revealed a single gfSL mRNA transcript of approximately 1 kb in the pituitaries of both sexually regressed and maturing male and female goldfish.
...
PMID:Sequence of a cDNA clone encoding a novel somatolactin in goldfish, Carassius auratus. 912 64

The effects of prolactin (PRL) on proliferation of cultured human uterine leiomyoma-derived smooth muscle cells (SMC) and its mechanism of action were investigated. PRL stimulated DNA synthesis and the expression of PRL receptor was identified by ribonuclease protection assay. Moreover, the regulation of mitogen-activated protein (MAP) kinase by PRL in leiomyoma-derived SMC was investigated. PRL stimulated MAP kinase activity, as detected by 32P incorporation into MAP-2, in a dose-dependent manner. PRL also rapidly stimulated MAP kinase phosphorylation as detected by in vivo phosphorylation using 32P labeling and phosphotyrosine immunoblotting. These results suggest that PRL stimulates the proliferation of human leiomyoma cells via the MAP kinase cascade.
...
PMID:Prolactin stimulates mitogen-activated protein kinase in human leiomyoma cells. 929 34

It is now widely accepted that the mammary gland is under interconnected hormonal and local control. Growth factors are involved in the intercellular signalling of the gland. Our aim was the detection of transforming growth factors alpha (TGF-alpha) and beta 1 (TGF-beta 1) messenger RNA during mammogenesis, lactogenesis, galactopoiesis and involution in the bovine mammary gland (total n = 27). During these stages the RNA was assessed by means of ribonuclease protection assay and reverse transcription-polymerase chain reaction (RT-PCR). To study possible influences of oestrogen, progesterone and prolactin on growth factor expression, mammary RNA was obtained from heifers after induced mammogenesis and lactogenesis, with and without additional prolactin inhibition (total n = 20). Very low levels of TGF-alpha and TGF-beta 1 expression were detected during lactogenesis and galactopoiesis, increasing levels during mammogenesis of primigravid heifers, and highest levels during mammogenesis of virgin heifers and during involution. TGF-alpha expression after induced mammogenesis was greater than after induced lactogenesis or physiological mammogenesis during pregnancy. Furthermore, TGF-alpha mRNA contents increased after prolactin inhibition. TGF-beta 1 expression was almost equal after induced mammogenesis and lactogenesis, but greater than during the physiological mammogenesis and lactogenesis. In conclusion, it can be assumed that growth promoting TGF-alpha and growth inhibiting TGF-beta 1 are co-expressed in the bovine mammary gland. Higher mRNA contents of both factors during mammogenesis and involution may indicate autocrine or paracrine functions for these growth factors during proliferation and reorganisation of the mammary tissue.
...
PMID:Expression of transforming growth factors alpha and beta-1 messenger RNA in the bovine mammary gland during different stages of development and lactation. 948 95


1 2 3 Next >>

---