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:1.11.1.7 (peroxidase)
65,474 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

Twelve human and twelve rat pituitaries were stained by an immunohistochemical method using a rabbit anti-ovine prolactin serum, a rabbit anti-human growth hormone serum and a sheep anti-rabbit immunoglobulin serum conjugated with horseradish peroxidase. On the same pituitary section, growth hormone cells were stained brown by using 3-3'-diaminobenzidine as peroxidase substrate, and prolactin cells were stained purplish blue by using 4-chloro-1-naphtol. Growth hormone cells outnumbered prolactin cells, especially in human pituitaries where the proportion is at least 10:1. No cells containing both brown granules stained for growth hormone and blue granules stained for prolactin were found in any of the sections examined. In the fetal pituitaries, there was no apparent hypertrophy of the prolactin cells, although the circulating levels of the hromone are known to be as high in the fetus at term as in the mother and much higher than in nonpregnant women.
...
PMID:Comparative immunoenzymatic localization of prolactin and growth hormone in human and rat pituitaries. 6 Dec 40

Thyrotropin-releasing hormone (TRH) immunoreactivity was localized in the rat anterior pituitary with rabbit anti-TRH sera and the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique. Stain was present in secretory granules of cells possessing morphological characteristics of thyrotropes, gonadotropes and lactotropes. Antibody absorption studies with anti-TRH sera absorbed with TRH, 3 diastereoisomeric analogues of TRH, gonadotropin-releasing hormone (GnRH), bovine serum albumin, thyrotropin, prolactin, adrenocorticotropin, luteinizing hormone, follicle stimulating hormone were performed to determine the specificity of the staining reaction. Only absorption with TRH resulted in a significant reduction in staining intensity. In vitro experiments were then begun with hemipituitaries to ascertain if intrapituitary TRH might originate by sequestration of exogenous, plasma membrane bound TRH or by de novo synthesis. The results suggest that anterior pituitary TRH is of endogenous origin.
...
PMID:Endogenous thyrotropin-releasing hormone in the anterior pituitary: sites of activity as identified by immunocytochemical staining. 8 70

A double antibody solid-phase (DASP) and a plyethylene glycol (PEG) radioimmunoassay method for plasma prolactin determination were developed and evaluated as to their reliability. The iodination of prolactin was carried out using a lactoperoxidase sorbent with iodination conditions being optimized by studying the effect of reaction buffer pH in the range 5.0--7.0 at two ionic strengths. With the DASP-technique, intra-assay coefficient of variation was 6% (n = 30) and the inter-assay coefficient of variation 12% (n = 12), and with the PEG-technique, intra-assay coefficient of variation was 10% (n = 10). The sensitivity, with the DASP system, was 0.098 ng/tube and the detection limit for plasma, 0.8 microgram/l. The use of the PEG-technique was abandoned because of poor precision and nonparallelism of plasma dilution curves with the standard curve. The whole mean basal plasma value was 34.0 +/- 19.5 microgram/l (mean +/- 2SD, n = 35). The response after administration of 200 mg sulphiride was an increase of between 119--220% of basal values and after administration of 100 mg of chlorpromazine, an increase of 85--140%. After administration of TRH (thyrotropine releasing hormone) an increase of between 60 and 330% was obtained, the mean increments after 20 min in outpatients being 87.0 microgram/l and in hospitalized subjects, 51.2 microgram/l.
...
PMID:Studies on the determination of plasma prolactin. 9 20

Ultrastructural documentation of the formation of coated vesicles in prolactin cells of the rat anterior pituitary gland is presented. Coated vesicles were observed forming from the secretory granular membrane in the Golgi area and between the Golgi complex and the plasmalemma. They were also found budding off the membrane lining the exocytotic pocket. Following peroxidase reaction product could be seen forming from the membrane of the exocytotic pocket and adjacent to it. These vesicles were found in transit towards the Golgi area or within lysosomes. It is proposed that these coated vesicles are important for membrane conservation and that this is occurring in developing secretory granules near the Golgi complex, in more mature secretory granules and at the level of the plasmalemma during exocytosis.
...
PMID:Coated vesicles in the rat anterior pituitary gland. 9 54

The rate of clearance from the circulation and uptake into tissues of radioactive label was studied after i.v. injection of 125-I-labelled human placental lactogen (HPL) into rats at various stages of pregnancy. The half-life was obtained for the disappearance of the trichloroacetic acid-precipitable material from the plasma. The half-life, t1/2(S), calculated over the first 5 min after injection of the hormone was 5.4 equals or minus 1.1 (S.D.) min, while a half-life, t1/2(L), of 27.9 equals or minus 2.3 min was obtained from the decay period of 15-35 min. In the non-pregnant and pregnant rat the highest ratio of the radioactivity in an organ to that in the blood was 12-14:1 in the kidney. That the kidney is mainly involved in the uptake of exogenous HPL is further confirmed by the application of the histochemical immunoperoxidase technique. Human placental lactogen was localized in the cells of the proximal tubules of the cortex and to a lesser extent in the tubular lumen and the tubules of the medulla region. UPTAKE OF HPL in vivo occurs in the mammary gland tissue of the post-partum rat and reaches a maximum uptake between 15 and 30 min after injection of the hormone. Furthermore, specific uptake of HPL was observed on the alveolar cell membranes after the incubation of paraffin-embedded sections of formalin-fixed mammary gland and subsequent treatment by the peroxidase-labelled antibody method. These findings support the work of others who have demonstrated the presence of specific membrane receptors in the mammary gland for hormones with prolactin-like activity.
...
PMID:Uptake of 125-I-labelled human placental lactogen and human placental lactogen by the tissues of normal and lactating rats. 16 83

A highly specific and sensitive radioreceptor assay for FSH has been developed, using partially purified plasma membranes from bovine testes. Highly purifed hFSH was radioiodinated by the lactoperoxidase method. The limit of detection of purified hFSH was 1 ng/ml on the basis of 2 times standard deviation of the zero value. The assay was applicable for measurements of FSH in serum; however, the sensitivity decreased slightly to 2.5 ng/ml. The precision of the assay was less than +/- 10% within-assays and +/- 15% between-assays as expressed by the coefficient of variation. The assay was highly specific for FSH of various species. Slight inhibition of uptake of 125I-hFSH was observed with LH and TSH; but no competition was seen with 10,000 ng/ml of insulin, prolactin, hGH, hCG, and subunits of LH. Purified hFSH (LER-1575C) was measured to be 200 times the potency of the reference FSH/LH (LER-907); and purified ovine FSH (LER-1491) and rat FSH (FSH-I-1) were estimated to be 35 times and 71 times that of oFSH-S-1 (NIH), respectively. The content of FSH in human pituitary was estimated to be 226.8 +/- 118.8 mIU/mg, and the index of discrimination (radioimmunoassay/radioreceptor assay) for pituitary FSH was demonstrated to be 1.71 +/- 0.49. For measurements of serum hFSH, the index of discrimination (radioimmunoassay/radioreceptor assay) was demonstrated to be 1.08 +/- 0.20.
...
PMID:A radioreceptor assay for follicle-stimulating hormone. 16 91

Specific prolactin (PRL) binding activity of lactoperoxidase catalyzed 125I-labeled ovine-PRL was determined in a membrane-rich particulate fraction of pigeon crop sacs. Levels of TSH, LH or FSH as high as 1000 ng each were unable to displace the 125I-o-PRL bound to 600 mug of crop sac microsomal protein, whereas competitive displacement was achieved with as little as 0.5 ng unlabeled PRL. Ovine GH exhibited some cross reactivity when incubated in amounts greater than 500 ng, but this could be accounted for by its stated PRL contamination. Specific PRL binding activities were determined in juvenile and mature pigeons with unstimulated crop sacs, and parent pigeons with 'crop milk' and mature birds injected with PRL for 4 days. Crop sacs from juvenile birds contained approximately twice as much binding activity as crop sacs from mature pigeons. Parent and PRL injected pigeons, each with proliferated crop sac epithelium, exhibited 4-5 times as much specific PRL binding as the non-proliferated crops from juvenile or mature birds. These results show that the pigeon crop sac contains specific binding sites for PRL, and that the crop sac response to PRL is associated with an increase in PRL binding activity.
...
PMID:Prolactin binding activity on the crop sacs of juvenile, mature, parent and prolactin-injected pigeons. 17 Nov 36

Prolactin iodinated by lactoperoxidase method showed immunologically, electrophoretically and biolo9gically similar properties to native prolactin and possessed enough specific radioactivity for receptor studies. 1251-prolactin was incubated with mouse mammary tissues at 8 days of lactation. Both binding and release of 1251-prolactin depended on incubation time and temperature and were maximal at 37 degrees C. Michaelis constant was estimated to be 1.4 X 10(-9) M from Lineweaver-Burk plot and to be 1.2 X 10(-9) M from id-value of the dose-response curve for displacement with native prolactin. Total number of binding sites for prolactin was 1.38 X 10(-15) mole per mg weight of tissue. Ovine prolactin, human growth hormone and human placental lactogen complete with 1251-prolactin and dose-response curves for these three hormones were all parallel. These results suggest the existence of a specific receptor site with high affinity for prolactin in lactating mouse mammary glands.
...
PMID:A receptor site for prolactin in lactating mouse mammary tissues. 17 1

Adenohypophysial primordia of rat embryos at 13 to 15 days gestation were cultured in Parker 199 synthetic medium for 2 to 11 days. At the end of the culture period their fine structure and the presence of immunoreactive trophic hormones using the peroxidase-labeled antibody technique were investigated. The degree of differentiation in the glands depends largely on the age of the embryos furnishing the explants. Cultured pituitaries explanted on the 13th day of gestation contain only ACTH-positive cells and about 15% of the cells are granular. The granules are 50-100 nm in diameter in some cells, while in other cells they range from 50 to 200 nm. In cultivated adenohypophysial primordia of embryos on the 15th day of intrauterine life ACTH, prolactin, LH and TSH cells are evident, but only the same two kinds of granular cells can be observed with the electron microscope. The extent of cytodifferentiation in the glands explanted on the 14th day of gestation is intermediate between the two other groups. The data suggest that the fetal rat pituitary has the capacity of self-differentiation but to a lesser extent than that of the in situ hypophysis.
...
PMID:Cell differentiation of the fetal rat anterior pituitary in vitro. 18 70


1 2 3 4 5 6 7 8 9 10 Next >>

---