SPECIFIC RECEPTORS FOR PROLACTIN IN THE OVARY

1975 ◽  
Vol 80 (1) ◽  
pp. 126-137 ◽  
Author(s):  
Tokuko Saito ◽  
Brij B. Saxena
Keyword(s):  
Protein Concentration ◽  
Plasma Membranes ◽  
Ovarian Function ◽  
Specific Binding ◽  
Receptor Protein ◽  
Tissue Homogenate ◽  
Mammary Tissue ◽  
Number Of Binding Sites ◽  
Specific Receptors

ABSTRACT A role of prolactin (PRL) in ovarian function has been suggested in several species, but not unequivocally established except in the rat. We, therefore, examined the presence of specific receptor for PRL in ovaries of rat, cow, and human. Human PRL (hPRL) labelled with 125I by the lactoperoxidase method was shown to be capable of specific binding to rat mammary tissue homogenate. Human, cow, and rat ovarian homogenates and/or partially purified plasma membranes were also shown to specifically bind 125I-hPRL. Binding was a saturable phenomenon and was dependent on receptor protein concentration. Optimal binding was observed at pH 7.0 and at 37°C. Binding was reversibly inhibited by exposure of membranes to pH 10.0 and irreversibly destroyed by exposure to pH 3.0. Bound 125I-hPRL was displaceable by unlabelled human, ovine, and bovine PRL but not by FSH or LH. However, human chorionic somatomammotrophin (hCS) and hGH showed some competition with 125I-hPRL. Number of binding sites/mg protein was lowest (0.8 × 10−12 m) during metoestrus and increased during dioestrus (11 × 10−12 m) reaching the maximum number at pro-oestrus (24.6 × 10−12 m). These results demonstrate that presence of specific PRL receptor in the ovaries and are consistent with a role of PRL at the ovarian level.

Effects of hypophysectomy and GH administration on bovine and human GH binding to rat liver membranes

1985 ◽  
Vol 249 (1) ◽  
pp. E56-E62
Author(s):  
J. L. Messina ◽  
S. Eden ◽  
J. L. Kostyo
Keyword(s):  
Binding Sites ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Human Growth ◽  
Male Rats ◽  
Normal Male ◽  
Number Of Binding Sites ◽  
Liver Membranes ◽  
Isolated Liver

Experiments were conducted to investigate the specific binding of highly purified bovine and human growth hormones (bGH and hGH) to purified liver plasma membranes of male rats at various times after hypophysectomy and after the acute intravenous administration of bGH. Liver membranes prepared from hypophysectomized male rats showed a two- to threefold increase in the specific binding of either [125I]iodo-bGH or [125I]iodo-hGH, when compared with membranes prepared from the livers of age-matched normal male rats. The increase in GH binding was apparent within 3 days after hypophysectomy and persisted for a number of weeks after the operation. The increase in GH binding produced by hypophysectomy appeared to be due to an increase in the number of binding sites present on the membranes. The intravenous injection of 200 micrograms of bGH into hypophysectomized male rats 5-60 min before they were killed markedly reduced the ability of liver membranes prepared from these animals to bind [125I]iodo-bGH specifically. This decrease in GH binding seen after the injection of bGH may have been due to the development of a slowly dissociating hormone-binding site complex, which thereby reduced the number of available binding sites. This conclusion is supported by the finding that bGH, which is bound in vitro to isolated liver membranes, dissociates slowly and incompletely in the presence of an excess of unlabeled hormone. Moreover, the degree to which the bound hormone can dissociate appears to depend on the length of time that association is allowed to occur.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Sphingomyelin Levels in the Plasma Membrane Correlate with the Activation State of Muscle Satellite Cells

2006 ◽  
Vol 54 (4) ◽  
pp. 375-384 ◽  
Author(s):  
Yosuke Nagata ◽  
Hideshi Kobayashi ◽  
Masato Umeda ◽  
Naoshi Ohta ◽  
Seiichiro Kawashima ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Satellite Cells ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Postnatal Growth ◽  
Bioactive Lipids ◽  
Specific Binding Protein ◽  
C2c12 Muscle Cells

Satellite cells are responsible for postnatal growth, hypertrophy, and regeneration of skeletal muscle. They are normally quiescent, and must be activated to fulfill these functions, yet little is known of how this is regulated. As a first step in determining the role of lipids in this process, we examined the dynamics of sphingomyelin in the plasma membrane. Sphingomyelin contributes to caveolae/lipid rafts, which act to concentrate signaling molecules, and is also a precursor of several bioactive lipids. Proliferating or differentiated C2C12 muscle cells did not bind lysenin, a sphingomyelin-specific binding protein, but noncycling reserve cells did. Quiescent satellite cells also bound lysenin, revealing high levels of sphingomyelin in their plasma membranes. On activation, however, the levels of sphingomyelin drop, so that lysenin did not label proliferating satellite cells. Although most satellite cell progeny differentiate, others stop cycling, maintain Pax7, downregulate MyoD, and escape immediate differentiation. Importantly, many of these Pax7-positive/MyoD-negative cells also regained lysenin binding on their surface, showing that the levels of sphingomyelin had again increased. Our observations show that quiescent satellite cells are characterized by high levels of sphingomyelin in their plasma membranes and that lysenin provides a novel marker of myogenic quiescence.

Insulin binding to liver plasma membranes in salmonids with modified plasma insulin levels

1991 ◽  
Vol 69 (11) ◽  
pp. 2745-2750 ◽  
Author(s):  
Joaquim Gutiérrez ◽  
Erika M. Plisetskaya
Keyword(s):  
Binding Affinity ◽  
Plasma Insulin ◽  
Plasma Membranes ◽  
Coho Salmon ◽  
Binding Capacity ◽  
Specific Binding ◽  
Insulin Binding ◽  
Term Treatment ◽  
Liver Plasma Membranes ◽  
Number Of Binding Sites

Insulin binding to the liver plasma membranes was assessed in coho salmon (Oncorhynchus kisutch) injected intraperitoneally with 6.6 μmol arginine/g body weight, and in rainbow trout (Oncorhynchus mykiss) fasted for 40 days and then refed for 15 days. Corresponding control groups of fish were injected with saline (coho salmon) or fed regularly (trout). Arginine injection was followed by a substantial elevation of plasma insulin titres from 12.5 to 76.8 ng/mL, an increase in the binding capacity and, consequently, an increase in specific binding of insulin to the liver plasma membranes from 3.4 to 5.5%. The binding affinity remained unchanged. Food deprivation lowered plasma insulin titres from 13.2 to 3.0 ng/mL, increased the binding capacity, but decreased the binding affinity, so the specific binding remained essentially unchanged (5.6% in fed versus 5.1% in fasted fish). Refeeding of fasted fish resulted in restoration of insulin levels and an increase in binding affinity relative to both control and fasted groups of fish. This led to a substantial elevation of the specific binding of insulin up to 7.1%. The binding of insulin to liver plasma membranes in salmonids depends both on the number of binding sites (binding capactity) and on the binding affinity. Long-term treatment, such as food deprivation, resulted in altered affinity and capacity of binding, whereas short-term treatment, such as arginine injection, affected mostly the binding capacity. Modulation of the number of binding sites in liver plasma membrane according to the insulin level was observed only in experiments on trout conducted at a higher (15 °C) water temperature.

Glucagon-like peptide-1 binding to rat hepatic membranes

1995 ◽  
Vol 146 (1) ◽  
pp. 183-189 ◽  
Author(s):  
M L Villanueva-Peñacarrillo ◽  
E Delgado ◽  
M A Trapote ◽  
A Alcántara ◽  
F Clemente ◽  
...  
Keyword(s):  
Protein Concentration ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Rat Hepatocytes ◽  
Binding Activity ◽  
Isolated Rat Hepatocytes ◽  
Sds Page ◽  
Pancreatic B Cells ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Abstract We have found [125I]glucagon-like peptide (GLP)-1(7–36)amide specific binding activity in rat liver and isolated hepatocyte plasma membranes, with an Mr of approximately 63 000, estimated by cross-linking and SDS-PAGE. The specific binding was time- and membrane protein concentration-dependent, and equally displaced by unlabelled GLP-1(7–36)amide and by GLP-1(1–36)amide, achieving its ID50 at 3×10−9 m of the peptides. GLP-1(7–36)amide did not modify the basal or the glucagon (10−8 m)-stimulated adenylate cyclase in the hepatocyte plasma membranes. These data, together with our previous findings of a potent glycogenic effect of GLP-1(7–36)amide in isolated rat hepatocytes, led us to postulate that the insulin-like effects of this peptide on glucose liver metabolism could be mediated by a type of receptor probably different from that described for GLP-1 in pancreatic B-cells or, alternatively, by the same receptor which, in this tissue as well as in muscle, uses a different transduction system. Journal of Endocrinology (1995) 146, 183–189

scholarly journals The relation between lipid mobility and the specific hormone binding of thyroid membranes

1975 ◽  
Vol 146 (2) ◽  
pp. 473-479 ◽  
Author(s):  
C L Bashford ◽  
S J Harrison ◽  
G K Radda ◽  
Q Mehdi
Keyword(s):  
Plasma Membranes ◽  
Membrane Lipids ◽  
Specific Binding ◽  
Thyroid Stimulating Hormone ◽  
Human Thyroid ◽  
Hormone Binding ◽  
Cortical Cells ◽  
Lipid Mobility ◽  
Number Of Binding Sites ◽  
Adrenal Cortical Cells

1. The specific binding of thyroid-stimulating hormone to isolated human thyroid membranes was examined under a variety of conditions. 2. In phosphate-saline buffer (in the presence of 0.14 M-NaCl) on increasing the temperature the binding of the hormone is increased, the plots of bound/free hormone against temperature showing a distinct break around 30 degrees C. 3. Detailed analysis showed that the increased binding is associated with an increase in the number of binding sites. 4. The motional characteristics of three membrane-bound fluorescent probes, 2-(9-anthroyl)palmitic acid, 12-(9-anthryl)stearic acid and N-1-naphthyl-N-phenylamine, were also examined as a function of temperature by measuring both fluorescence polarizations and lifetimes. 5. The results indicated that the ‘fluidity’ of membrane lipids also increased with temperature. The temperature-dependence of this property also shows a change at about 30 degrees C. 6. Bivalent cations decreased both membrane fluidity and hormone binding. 7. Similar correlations were found between the binding of adrenocorticotrophic hormone and the fluidity of the plasma membranes obtained from adrenal-cortical cells, with the discontinuity occurring in this case at 23 degrees C. 8. The possibility of lipid mobility being important in controlling hormone-receptor function is discussed.

scholarly journals Properties of follicle-stimulating-hormone receptor in cell membranes of bovine testis

1975 ◽  
Vol 149 (1) ◽  
pp. 123-132 ◽  
Author(s):  
K W Cheng
Keyword(s):  
Plasma Membranes ◽  
Specific Binding ◽  
Follicle Stimulating Hormone ◽  
Binding Activity ◽  
Receptor Protein ◽  
Temperature Dependent ◽  
Irreversible Damage ◽  
Simple Method ◽  
Testicular Receptor ◽  
Stimulating Hormone

A simple method for preparing plasma membranes from bovine testes is described. Bovine testicular receptor has a high affinity and specificity for 125I-labelled human FSH (follicle-stimulating hormone). The specific binding of 125I-labelled human FSH to the plasma membranes is a saturable process with respect to the amounts of receptor protein and FSH added. The association and dissociation of 125I-labelled human FSH are time- and temperature-dependent, and the binding of labelled human FSH to bovine testicular receptor is strong and not readily reversible. Scatchard [Ann. N.Y. Acad. Sci. (1949) 51, 660-672] analysis indicates a dissociation constant, Kd, of 9.8 ×10-11M, and 5.9 × 10-14mol of binding sites/mg of membrane protein. The testicular membrane receptor is heat-labile. Preheating at 40°C for 15 min destroyed 30% of the binding activity. Specific binding is pH-dependent, with an optimum between pH 7.0 and 7.5. Brief exposure to extremes of pH caused irreversible damage to the receptors. The ionic strength of the incubation medium markedly affects the association of 125I-labelled human FSH with its testicular receptor. Various cations at concentrations of 0.1M inhibit almost completely the binding of 125I-labelled human FSH. Nuclectides and steroid hormones at concentrations of 1mM and 5 μg/ml respectively have no effect on the binding of FSH to its receptor. Incubation of membranes with and chymotrypsin resulted in an almost complete loss of binding activity, suggesting that protein moieties are essential for the binding of 125I-labelled human FSH. Binding of 125I-labelled human FSH to bovine testicular receptor does not result in destruction or degradation of the hormone.

INTERACTION OF [125I]LH-RH AND OTHER OLIGOPEPTIDES WITH PLASMA MEMBRANES OF RAT ANTERIOR PITUITARIES

1979 ◽  
Vol 92 (2) ◽  
pp. 228-241 ◽  
Author(s):  
Rudolf Baumann ◽  
Herbert Kuhl
Keyword(s):  
Pituitary Gland ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Specific Binding ◽  
Biological Activities ◽  
Single Type ◽  
Number Of Binding Sites ◽  
Specificity Of Binding ◽  
Lh Rh

ABSTRACT The specific binding of [125I]LH-RH to isolated plasma membranes of rat pituitaries was investigated. The binding process was found to be highly specific, temperature-dependent and saturable. The dissociation constant as calculated by three different methods was approximately 1.3 · 10−8 m, indicating a single type of binding sites. Maximal binding capacity was 1 · 10−12 moles/mg protein (=2 ng LH-RH/pituitary gland), and the number of binding sites was calculated to be 6 · 1011 per mg membrane protein (= 1 · 1010 binding sites/pituitary gland). When diluted with icecold buffer the dissociation of specifically bound LH-RH occurred very rapidly (half-life 3.17 min) with a rate constant of 0.219 min−1. The dissociation process followed first-order kinetics. Specificity of binding was demonstrated by dose-dependent competition of unlabelled LH-RH, the highly potent analogue D-glutamine-(cyclohexyl)6-LH-RH-nonapeptide-ethylamide and the fragment of an analogue (6-D-Ser(TBu))-LH-RH-(3-9)-heptapeptide-ethylamide with the binding [125I]LH-RH, while angiotensin I, II, oxytocin and bacitracin did not compete. The affinities of LH-RH and the analogue to the binding sites of the pituitary plasma membranes were not consistent with the respective biological activities.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

Regulatory role of resistin on ovarian function

2014 ◽  
Author(s):  
Agnieszka Rak-Mardyla ◽  
Anna Wrobel ◽  
Eliza Drwal ◽  
Ewa Gregoraszczuk
Keyword(s):  
Ovarian Function ◽  
Regulatory Role

scholarly journals Endothelial Dysfunction in Diabetes Is Aggravated by Glycated Lipoproteins; Novel Molecular Therapies

Biomedicines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Laura Toma ◽  
Camelia Sorina Stancu ◽  
Anca Volumnia Sima
Keyword(s):  
Plasma Proteins ◽  
Diabetes Complications ◽  
Vascular Complications ◽  
High Density Lipoproteins ◽  
Diabetic Patients ◽  
Inflammatory Stress ◽  
Glycation End Products ◽  
Molecular Therapies ◽  
Specific Receptors

Diabetes and its vascular complications affect an increasing number of people. This disease of epidemic proportion nowadays involves abnormalities of large and small blood vessels, all commencing with alterations of the endothelial cell (EC) functions. Cardiovascular diseases are a major cause of death and disability among diabetic patients. In diabetes, EC dysfunction (ECD) is induced by the pathological increase of glucose and by the appearance of advanced glycation end products (AGE) attached to the plasma proteins, including lipoproteins. AGE proteins interact with their specific receptors on EC plasma membrane promoting activation of signaling pathways, resulting in decreased nitric oxide bioavailability, increased intracellular oxidative and inflammatory stress, causing dysfunction and finally apoptosis of EC. Irreversibly glycated lipoproteins (AGE-Lp) were proven to have an important role in accelerating atherosclerosis in diabetes. The aim of the present review is to present up-to-date information connecting hyperglycemia, ECD and two classes of glycated Lp, glycated low-density lipoproteins and glycated high-density lipoproteins, which contribute to the aggravation of diabetes complications. We will highlight the role of dyslipidemia, oxidative and inflammatory stress and epigenetic risk factors, along with the specific mechanisms connecting them, as well as the new promising therapies to alleviate ECD in diabetes.

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