Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Araldite sections of male rat pituitaries, stained after embedding by the unlabeled antibody enzyme method with antisera to native luteinizing hormone-releasing hormone (LH-RH) or LH-RH azo-conjugated to bovine serum albumin, localization is confined mainly to the interior of the large, and to a lesser extent to that of the small, secretion granules of the gonadotrophic cells. Plasma membranes are not demonstrated. Except for weak staining in the granules of corticotrophs, no other pituitary cell is stained. Pretreatment of sections with LH-RH (to dilutions of 4 pg/mul) increases staining intensity in the gonadotrophic granules. Other cells are unaffected. The lesser the gonadotroph staining intensity without pretreatment, the greater the increase (more than 23-fold reactivity). Augmented staining is measurable (P less than 0.001) to antiserum dilutions of 1:240000. Pretreatment with des-Glu-1-LH-RH, porcine corticotropin or rat prolactin has no effect. LH-RH-Gly-10(des-amide) inhibits. Rat glycoprotein hormones enhance staining with anti-azo-conjugated LH-RH. With antinative LH-RH these hormones enhance weak staining, but inhibit strong staining. Thick vibrotome sections of male rat or rabbit pituitaries stained before embedding reveal specific localization on plasma membrane and gonadotrophic secretion granules provided the sections have been pretreated with LH-RH (250 pg/mul). The data show that LH-RH after reaction with receptor is not sterically hindered from binding specific antibodies. Receptor may be found in secretion granules, both in the free state or combined with LH-RH. Plasma membrane receptor, on the other hand, was free under the conditions of the experiments. Immunization with LH-RH elicits not only heteroimmune antibodies specific for LH-RH, but also a group of still ill defined autoimmune antibodies, some of which may conceivably be reactive with glycoprotein hormone alpha-chains.
 ...
PMID:Quantitative immunocytochemistry of pituitary receptors for luteinizing hormone-releasing hormone. 5 7

The storage sites of the pituitary glycoprotein hormones were identified with the use of electron microscopic immunocytochemical techniques and antisera to the beta (beta) chains of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH). The TSH cells in normal rats is ovoid or angular and contains small granules 60-160 nm in diameter. In TSH cells hypertrophied 45 days after thyroidectomy, staining is in globular patches in granules or diffusely distributed in the expanded profiles of dilated rough endoplasmic reticulum. The gonadotrophs (FSH and LH cells) exhibited three different morphologies. Type I cells are ovoid with a population of large granules and a population of small granules. Staining for FSHbeta or LHbeta was intense and specific only in the large granules (diameter of 400 nm or greater). Type II cells are angular or stellate and contain numerous secretory granules averaging 200-220 nm in diameter. They predominate during stages in the estrous cycle when FSH or LH secretion is high. Type III cells look like adrenocorticotropin (ACTH) cells in that they are stellate with peripherally arranged granules. They generally stain only with anti-FSHbeta and their staining can not be abolished by the addition of 100 ng ACTH. In preliminary quantitative studies of cycling females, we found that on serial sections FSH cells and LH cells show similar shifts to a more angular population of cells during stages of active secretion. However, the shifts are not in phase with one another. Furthermore, there are at least 1.5 times more FSH cells than LH cells at all stages of the cycle. Our collection of serial cells shows that some cells (usually type I or II) stain for both gonadotropic hormones, whereas others (usually type II or III) contain only one.
 ...
PMID:Immunocytochemistry of the pituitary glycoprotein hormones. 6 Apr 35

Recent immunohistochemical demonstration of calcitonin in rat pituitary has suggested that calcitonin, in addition to ACTH, endorphins, lipotropins, and melanocyte-stimulating hormones might be derived from a 31,000-dalton glycoprotein percursor molecule. This immunoperoxidase study demonstrates a similar distribution for beta-endorphin and ACTH immunoreactivity in human pituitary; however, the two peptides are not necessarily present in the same cells at all times. Calcitonin could not be demonstrated in human pituitary under conditions suitable for demonstration of the peptide in thyroid C cells. Weakly positive immunostaining could be obtained only with much increase in antiserum concentration and length of incubation, and higher concentrations of calcitonin were needed to abolish staining in preabsorption studies. It thus appears that the immunoreactive calcitonin in human pituitary differs from that in thyroid C cells. Likewise, we could not demonstrate immunoreactive endorphin in any developmental stage of medullary thyroid carcinoma. Our study suggests that caution should be applied in considering a physiologic role for calcitonin in the pituitary and in postulating a common peptide origin for endorphin and calcitonin in humans.
 ...
PMID:Distribution of beta-endorphin immunoreactivity in normal human pituitary. 22 39

Cholera toxin, through adenylate cyclase activation reproduced cyclic AMP-mediated effects of thyroid-stimulating hormone (TSH) in dog thyroid slices, i.e. protein iodination, [1-14C]glucose-oxidation and hormone secretion. Iodide and carbamylcholine decreased the cyclic AMP accumulation induced by cholera toxin as well as by TSH, which supports the hypothesis of an action of these agents beyond the steps of hormone-receptor and receptor-adenylate cyclase interaction. Cooling to 20 degrees C did not impair the TSH induced cyclic AMP accumulation in thyroid slices, but completely suppressed the cholera toxin effect. This observation has been extended to other hormones and target tissues, such as the parathyroid hormone (PTH) (kidney cortex), adrenocorticotropic hormone (ACTH) (adrenal cortex) and luteinizing hormone (LH) (ovary systems). As in thyroid, cooling dissociated the cholera toxin and hormonal effects on cyclic AMP accumulation. In homogenate, cooling decreased cyclic AMP generation in the presence of cholera toxin but at 20 degrees C and 16 degrees C a cholera toxin stimulation was still observed. These results bear strongly against the hypothesis that the glycoprotein hormones TSH and LH acetivate adenylate cyclase by a mechanism identical to cholera toxin.
 ...
PMID:Dissociation by cooling of hormone and cholera toxin activation of adenylate cyclase in intact cells. 22 51

The neurointermediate lobes of dark adapted toads, Xenopus laevis, were incubated for 30 min in [3H]arginine, [3H]arginine plus [14C]glucosamine, or [3H]glucosamine and then chased for various time periods ranging from 1--3 h. The labeled polypeptides synthesized and secreted by the lobes were analyzed by acid-urea polyacrylamide gel electrophoresis. A glycosylated ACTH-endorphin precursor (32,000 mol wt) was synthesized during the pulse and identified by immunoprecipitation by ACTH-(11--24) antiserum. During the chase, this precursor was processed to various glycopeptides and peptides, including ACTH, beta-lipotropin, and alpha-MSH, which were subsequently secreted into the medium. An immunoprecipitable ACTH-related glycoprotein (approximately 150,000 mol wt) and other nonimmunoprecipitable glycoproteins (approximately 80,000--100,000 mol wt) were also synthesized and secreted by the neurointermediate lobe. The secretion of these glycoproteins and peptides was inhibited by dopamine. The significance of glycosylation of the precursor for the biosynthesis, processing, and secretion of the ACTH, beta-lipotropin-, and MSH-related peptides was examined by using a specific inhibitor of glycosylation, tunicamycin. Tunicamycin treatment did not affect the synthesis of the 32,000 mol wt ACTH-endorphin precursor but did prevent its glycosylation. The absence of carbohydrate on the precursor resulted in its rapid intracellular degradation. Precursors that escaped degradation were processed incompletely, leading to the formation and secretion of an unglycosylated intermediate and various other abnormal peptides. The data indicate that glycosylation of the ACTH-endorphin precursor may not be involved in the processes of intracellular transport, packaging, and secretion per se but, rather, may provide specific conformational stability to the precursor as a signal for directed limited proteolysis.
 ...
PMID:The role of the carbohydrate in the stabilization, processing, and packaging of the glycosylated adrenocorticotropin-endorphin common precursor in toad pituitaries. 22 74

In the pars intermedia of rat pituitary glands, two forms of a common precursor for corticotropin (ACTH) and beta-lipotropin with apparent molecular weights of 34,000 and 36,000 were resolved by sodium dodecyl sulfate/acrylamide gradient slab gel electrophoresis. High-performance liquid chromatographic analysis of [35S]methionine-labeled tryptic fragments of the two forms of the precursor revealed that both contained copies of ACTH-(1-8) and beta-lipotropin-(61-69) sequences. When biosynthetic studies were performed in the presence of tunicamycin, the 34,000- and 36,000-dalton forms were replaced by a peptide with an apparent molecular weight of 32,000. It was therefore concluded that the 34,000- and 36,000-dalton forms of the precursor represent two glycoprotein variants of similar polypeptides, differing in the number of asparagine-linked carbohydrate moieties. During pulse-chase incubations with [35S]methionine, the precursor forms were cleaved into two major groups of labeled products: (i) beta-endorphin and (ii) a mixture of ACTH fragments closely related to alpha-melanotropin. No ACTH-(1-39) was found at the end of a 2-hr chase period, suggesting that ACTH is not a significant hormone product of the rat pars intermedia.
 ...
PMID:Concomitant synthesis of beta-endorphin and alpha-melanotropin from two forms of pro-opiomelanocortin in the rat pars intermedia. 22 77

Human placental villus tissue contains opioid receptors and peptides. Kappa opioid receptors (the only type present in this tissue) were purified with retention of their binding properties. The purified kappa receptor is a glycoprotein with an apparent molecular weight of 63,000. Two opioid receptor mediated functions were identified in trophoblast tissue, namely regulation of acetylcholine and hormonal (human chorionic gonadotrophin and human placental lactogen) release. Placental content of kappa receptors increases with gestational age. Term placental content of kappa receptors correlates with route of delivery (higher in those abdominally obtained). Opioid use and/or abuse during pregnancy affects placental receptor content at delivery, as well as its mediated functions. Opioid peptides identified in placental extracts were beta-endorphin, methionine enkephalin, leucine enkephalin and dynorphins 1-8 and 1-13. Dynorphin 1-8 seem to be the predominant opioid peptide present in placental villus tissue.
 ...
PMID:Properties and functions of human placental opioid system. 130 34

Intracellular proteolytic processing of fusion glycoprotein precursors (F0) of paramyxoviruses, i.e. a virulent strain of Newcastle disease virus (NDV), parainfluenza virus type 3 (PIV3) and simian virus 5 (SV5), was examined in NALM6 and BSC40 cells and compared with that in LLCMK2 cells to investigate the distribution of the virus-activating protease(s) among the cells and its substrate specificity. BSC40 cells lack a processing endoprotease of the neuropeptide precursor, pro-opiomelanocortin (POMC), which possesses multiple cleavage sites at pairs of basic residues, Lys-Arg and Arg-Arg, a motif similar to that found in the cleavage site of the F0 proteins. In NALM6 cells, only small amounts of the F0 protein of virulent NDV was cleaved whereas those of PIV3 and SV5 were efficiently cleaved. In BSC40 cells the F0 proteins of these three viruses were cleaved normally as well as in LLCMK2 cells. The processing inhibitors monensin, chloroquine and A23187 suppressed the F0 cleavage in the three cell types. These results indicate that both NALM6 and BSC40 cells possess virus-activating proteases similar to that of LLCMK2 cells, but suggest that the enzyme of NALM6 may be slightly different in its substrate specificity from those of BSC40 and LLCMK2. The results also suggest that the virus-activating proteases are different in their distribution and substrate specificity from the processing enzyme of POMC.
 ...
PMID:Distribution and substrate specificity of intracellular proteolytic processing enzyme(s) for paramyxovirus fusion glycoproteins. 131 18

We have determined that greater than or equal to 80% of the Asn-linked oligosaccharides on the glycosylated form of mouse adrenocorticotropin (15-kDa adrenocorticotropin (ACTH)) bear one or more branches terminating with the sequence SO4-4GalNAc beta 1,4GlcNAc beta 1,2Man alpha (S4GGnM). Proopiomelanocortin (POMC), the precursor of ACTH, is the first example of a glycoprotein that is not a member of the glycoprotein hormone family to bear such sulfated structures. Like lutropin and thyrotropin, 15-kDa ACTH bears dibranched oligosaccharides terminating with SO4-4-GalNAc; however, at least half of the oligosaccharides on 15-kDa ACTH terminating with SO4-4-GalNAc consist of more highly branched structures that have not previously been described. Both the GalNAc beta 1,4GlcNAc beta 1,2Man-4-sulfotransferase and the glycoprotein hormone-specific GalNAc-transferase are expressed in the corticotroph-derived AtT-20 cell line. A tripeptide recognition sequence, Pro-Val-Lys, similar to the Pro-Leu-Arg sequence required for recognition of glycoprotein hormone alpha- and beta-subunits by the glycoprotein hormone-specific GalNAc-transferase, is present 8 residues amino-terminal to the glycosylated Asn of 15-kDa ACTH. Thus, POMC has the features expected for specific addition of the S4GGnM sequence to its oligosaccharides. The recent discovery of a receptor in hepatic endothelial cells that recognizes oligosaccharides terminating with S4GGnM suggests these sulfated oligosaccharides will regulate the circulatory half-life of glycosylated POMC cleavage products.
 ...
PMID:Pro-opiomelanocortin synthesized by corticotrophs bears asparagine-linked oligosaccharides terminating with SO4-4GalNAc beta 1,4GlcNAc beta 1,2Man alpha. 161 97

A 19-year-old man with blurred vision, headache, and no signs or symptoms of hormone excess was found to have a pituitary adenoma. The tumor was removed by a transfrontal approach. He had postoperative radiation therapy, but subsequently had three recurrences, all removed surgically. By histology, the tumor was a chromophobic, slightly acidophilic pituitary adenoma. Immunohistochemistry revealed the presence of adrenocorticotropin (ACTH) in all four biopsies, alpha-subunit of glycoprotein hormones, and, to a lesser extent, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the third and fourth tumor resection specimens. Ultrastructurally, the tumor had typical features of a silent corticotroph adenoma subtype 2. In tissue culture, the second, third, and fourth specimens released ACTH, alpha-subunit, FSH, and LH and responded to corticotropin-releasing hormone with increased release of ACTH, alpha-subunit, FSH, and LH. To our knowledge only one silent corticotroph adenoma has been reported previously which expressed plurihormonality. Change in immunohistochemical profile in malignant tumors is a well-known phenomenon; however, it was not reported previously in benign pituitary adenomas. The factors accounting for changing tumor phenotype are unknown.
 ...
PMID:Changes in hormone production of a recurrent silent corticotroph adenoma of the pituitary: a histologic, immunohistochemical, ultrastructural, and tissue culture study. 164 19


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