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

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Throughout life, the ovarian surface epithelium (OSE) undergoes morphogenetic changes that may be hormonally regulated. To investigate this possibility, a population of cells morphologically identical to native OSE cells was isolated from estrous rabbits with collagenase, unit gravity sedimentation, and trypsin-EDTA. Cells were incubated with various concentrations of protein hormones in serum-rich medium or in a chemically defined medium containing fibronectin. Tritiated thymidine was added 24 h before interruption of cultures. Growth-promoting effects of tested hormones were more pronounced and consistent in serum-free cultures. Under these conditions, human chorionic gonadotropin (10,000 mIU/ml) caused a 2.8-fold increase in cell number and a 3.4-fold stimulation of thymidine incorporation. Luteinizing hormone (NIAMDD-oLH-24, 1.0 micrograms/ml) and follicle-stimulating hormone (NIADDK-oFSH-16, 1.0 micrograms/ml) produced, respectively, a 1.7-fold and 1.5-fold increase in cell proliferation, and over 1.4-fold and 1.3-fold stimulations of thymidine uptake. When used together, no growth stimulation by these gonadotropins was seen. Slight but significant increases in cell number (1.4-fold) and in radiolabel incorporation (1.3-fold) were observed with prolactin (NIADDK-oPrl-16, 10 ng/ml). These data indicate that some protein hormones promote the growth of OSE cells. This property may be important in regulating these cells during normal and pathologic states.
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PMID:Growth effects of protein hormones on cultured rabbit ovarian surface epithelial cells. 393 84

Bromocriptine in concentrations up to 5 X 10(-4) mol/L was studied for any deleterious effects upon normal rat pituitary cells, as well as on the rat GH3 cell line. Normal rat pituitary glands were obtained by decapitation from 50-day-old female Wistar rats and dispersed with 0.25% trypsin. The cells (10(5) per plate) were then incubated in 60 by 15 mm plates (Falcon) that contained 3 ml of Dulbecco's modified Eagle's medium with 10% fetal calf serum. GH3 cells were plated in a similar fashion. Bromocriptine was added in concentrations of 5 X 10(-4) to 5 X 10(-9) mol/L, and aliquots of medium were obtained at 6, 24, and 48 hours for the determination of growth hormone and prolactin. Cell counts were performed at 24 and 48 hours. A significant reduction in concentrations of growth hormone and prolactin was observed with concentrations of bromocriptine of 5 X 10(-5) and 5 X 10(-4) mol/L at 24 and 48 hours (p less than 001). Although no significant changes in cell counts were observed in the normal rat pituitary cells, the GH3 cells showed complete disruption at 48 hours only in the plates that contained the highest concentrations of bromocriptine. Electron microscopy of normal rat cells and GH3 demonstrated selective cytotoxic effects only on the GH3 cells. In conclusion, bromocriptine has been demonstrated to have a direct effect on hormone release and on the morphologic characteristics of tumor cells but not normal pituitary cells.
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PMID:Hormonal and morphologic effects of bromocriptine on normal rat pituitary and GH3 tumor cells. 405 Sep 9

Two CNBr fragments of sea whale prolactin containing 69 and 41 amino acid residues, respectively, were hydrolyzed by trypsin, and the hydrolytic products were separated by the paper peptide mapping technique. The amino acid sequence of 17 homogeneous peptides was studied by the Edman method as well as by hydrolysis with carboxypeptidases A and B. Based on the experimental data and the previously published results the primary structure of sea whale prolactin made up of 199 amino acid residues was proposed.
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PMID:[Primary structure of whale prolactin]. 405 10

A new procedure has been developed for dissociating anterior pituitary tissue and producing a viable suspension of single cells. The procedure involves incubation of small tissue blocks in 1 mg/ml trypsin (15 min), followed by incubation in 8 microg/ml neuraminidase and 1 mM EDTA (15 min), followed by mechanical dispersion. Cell yields are approximately 55%, based on recovered DNA. By electron microscopy five types of secretory cells (somatotrophs, mammotrophs, thyrotrophs, gonadotrophs, and corticotrophs) plus endothelial and follicular cells can be identified and are morphologically well preserved up to 20 h after dissociation. Throughout this period, the cells incorporate linearly [(3)H]leucine into protein for up to 4 h at a rate 90% greater than hemipituitaries, and they synthesize, transport intracellularly, and release the two major pituitary secretory products, growth hormone and prolactin. Immediately after dissociation the cells' ability to respond to secretogogues (high K(+) and dibutyryl cyclic AMP) is impaired, but after a 6-12-h culture period, the cells apparently recover and discharge 24% and 52%, respectively, of their content of prelabeled growth hormone over a 3-h period in response to these two secretogogues. This represents a stimulation of 109% and 470% over that released by cells incubated in control medium. The results demonstrate that function and morphologic integrity are preserved in this cell system. Therefore it is suitable for the study of various aspects of pituitary secretion and its control.
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PMID:Hormone secretion by cells dissociated from rat anterior pituitaries. 437 81

Receptors for human, simian, ovine, bovine and murine prolactin, human growth hormone and human placental lactogen have been identified in plasma-membrane-containing subcellular particles isolated from rabbit mammary glands. The association and dissociation of (125)I-labelled prolactin are time- and temperature-dependent processes, both being maximal at 37 degrees C. (125)I-labelled prolactin prepared by the enzymic iodination procedure with lactoperoxidase binds better to receptors than does the preparation obtained by using chloramine-t as the oxidizing agent. The binding of (125)I-labelled prolactin to receptors is strongly influenced by pH and ionic composition but not by many low-molecular-weight compounds tested, e.g. steroids, nucleotides and several drugs. Receptor activity is sensitive to trypsin and phospholipase C digestion, suggesting that protein and phospholipid moieties are essential for the binding of (125)I-labelled prolactin. The binding of (125)I-labelled prolactin to receptors is a saturable and reversible process. Scatchard and Lineweaver-Burk analyses suggest that (125)I-labelled prolactin has a high affinity for its receptor. Binding of (125)I-labelled prolactin to receptors does not result in the destruction of the hormone. Considerable prolactin-binding activity is also observed in subcellular fractions isolated from the adrenal gland, liver, ovary and kidney of the pregnant rabbit, a finding that is consistent with other reported actions of prolactin in these organs.
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PMID:Properties of a prolactin receptor from the rabbit mammary gland. 437 64

The occurrence of insulin receptors and biological responses to insulin has been investigated in trypsin-dissociated fetal rat brain cells maintained in culture for 8 days. Binding of [125I]insulin to brain cells in culture was time- and pH-dependent and 85--90% specific. Porcine insulin competed for [125I]insulin binding in a dose-dependent manner. Unrelated polypeptides, including angiotensin II, glucagon, bovine growth hormone, and bovine prolactin did not compete for [125I]insulin binding. The half-life of [125I]insulin dissociation from receptors at 24 degrees C was 15 min and a plot of In[B/Bo] vs time suggested two dissociated rate constants of 2.7 X 10(-4) sec-1 and 5.0 X 10(-5) sec-1. Scatchard analysis of the binding data gave a curvilinear plot which may indicate negative cooperativity or the occurrence of both high affinity (Ka = 2 X 10(11) M-1) and low affinity (Ka = 4 X 10(10) M-1) sites. Of the estimated total of 4.9 X 10(4) binding sites per cell, 28--30% appear to be high affinity sites. Incubation of cultures with insulin caused a time- and dose-dependent stimulation of [3H]thymidine and [3H]uridine incorporation into TCA-precipitable material. Maximum stimulation of thymidine incorporation (2--5-fold) occurred 11 h after incubation with 167 nM insulin. The same concentration of insulin caused a 2.2-fold increase in [3H]uridine incorporation in 2 h. These results indicate that cells cultured from rat brain contain specific insulin receptors capable of mediating effects of insulin on macromolecular synthesis in the central nervous system.
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PMID:Binding of [125I]insulin to specific receptors and stimulation of nucleotide incorporation in cells cultured from rat brain. 615 64

It has been previously demonstrated that commercial bacterial fibrinolysin (EC 3.4.21.7) selectively cleaves the bond between Met-53 and Ala-54 in ovine prolactin (199 amino acids). A one-step purification procedure on DEAE-cellulose for Protease F, which is the active component of bacterial fibrinolysin, and properties of the purified enzyme are reported. The enzyme is homogeneous as judged by acrylamide gel electrophoresis. Its molecular weight, calculated from gel filtration experiments on Sephadex G-100, is around 13,800. Amino acid analyses do not reveal the presence of any half-cystines. The presence of one tryptophan residue per enzyme molecule was resolved from the fluorescence spectrum. Amino terminal analysis showed that leucine was at the amino terminal position. Protease F hydrolyzes casein and synthetic specific substrates for chymotrypsin and elastase esterases but not for trypsin esterases. It is fully inhibited by phenylmethylsulfonyl fluoride, by chicken ovoinhibitor, and by Chymotrypsin Inhibitor I from potatoes but not by the trypsin-chymotrypsin inhibitors from soybeans and chick peas or by tosyl-L-phenylalanine chloromethyl ketone. The enzyme is stable at room temperature and in the cold, it is not affected by dialysis or by freezing and thawing, but it is inactivated during freeze-drying. The circular dichroism spectra of Protease F indicate an approximate 20% alpha-helix content of the enzyme with a considerable similarity to those of subtilisin, elastase, and beta-trypsin. The relatively low molecular weight of Protease F, the absence of intrachain disulfide bridges, and the fact that it is inhibited by several, but not all, chymotrypsin inhibitors suggest that it may differ phylogenetically from the known serine proteases.
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PMID:Purification and properties of protease F, a bacterial enzyme with chymotrypsin and elastase specificities. 622 44

The binding characteristics of ovine prolactin (OPRL) to a particulate fraction from liver and tail fin of Rana catesbeiana tadpoles were studied. The specific binding of [125I]oPRL to both tissues was found to be a saturable process with a single class of binding sites in each tissue. Although the dissociation constants were similar for each tissue, the tail fin demonstrated a 10-fold higher binding capacity than the liver tissue. Pretreatment of the liver and tail fin particulate fractions with degradative enzymes revealed that trypsin and phospholipase C reduced the subsequent specific [125I]oPRL binding in both tissues. However, neuraminidase treatment decreased the prolactin binding in the liver while having no effect on the tail fin. The binding of prolactin to the amphibian tissues was found to be specific for prolactin and growth hormones. [125I]oPRL binding to both tissues was a reversible process although the dissociation rate was faster for the tail fin than for the liver. Therefore, prolactin receptors are associated with both a prolactin responsive tissue, the tail, and an unresponsive tissue, the liver, in the tadpole.
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PMID:Prolactin and tadpole metamorphosis. Evidence of prolactin receptors in premetamorphic Rana catesbeiana liver and tail fin. 624 78

Rat pituitary cells were dispersed with trypsin and separated by sedimentation at unit gravity. The distributions of prolactin (Prl), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were determined, and two enriched cell populations (mammotrophs and gonadotrophs) were subsequently cultured. During a 4 h incubation, gonadotrophin-releasing hormone (GnRH) stimulated the release of LH and of FSH by both the unfractionated population and the enriched gonadotrophs; the magnitude of this stimulation increased with the length of the pre-culture periods, and the amount of LH released into the medium correlated strongly with the amount of FSH, whatever the length of the pre-culture period. The cellular cAMP content was also enhanced during the 4 h incubation, but no correlation was found between the hormone release and the cAMP accumulation. Furthermore, during the first 30 min of incubation with GnRH there was no increase of cellular cAMP, whatever cell population used. We conclude that the gonadotrophin release was independent of the cAMP accumulation observed in pituitary cells several hours after stimulation by GnRH; consequently, the late increase in the nucleotide is suggested to be a non-specific secondary process.
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PMID:Gonadotrophin release by gonadotrophs incubated with gonadotrophin-releasing hormone is independent of intracellular cAMP accumulation. 626 86

Membrane preparations of collagenase-dispersed Langerhans islets of female Wistar rats exhibit specific binding sites for 125I-labelled ovine prolactin (125I-oPrl). Almost negligible binding was detected in islets of male animals. The binding is a saturable and time-temperature dependent process, equilibrium being reached after 16 h incubation at 0 degrees C. The bound oPrl is not displaceable by hFSH, hLH, bGH or hGH. In contrast with other cell fractions, the 12,000 g pellet accounts for more than 80% of the specific binding of 125I-oPrl. Scatchard plots of data obtained in saturation studies indicate a single class of binding sites with Ka = 0.21 x 10(10)M-1. Protein and phospholipid moieties are essential for the receptor activity, since after trypsin or phospholipase C digestions marked loss of binding was verified. In islets of streptozotocin diabetic rats a marked reduction in the number of binding sites was observed. These findings may suggest that some of the actions of prolactin on endocrine pancreas could be explained by its specific interaction with islet cell membranes.
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PMID:Prolactin binding in rat Langerhans islets. 627 57


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