scholarly journals Thyroglobulin interactions with thyroid plasma membranes. The existence of specific receptors and their potential role.

1979 ◽  
Vol 254 (12) ◽  
pp. 5065-5076 ◽  
Author(s):  
E Consiglio ◽  
G Salvatore ◽  
J E Rall ◽  
L D Kohn
Keyword(s):  
Plasma Membranes ◽  
Potential Role ◽  
Specific Receptors

Extracellular ATP induces a nonspecific permeability of thymocyte plasma membranes

1989 ◽  
Vol 67 (9) ◽  
pp. 495-502 ◽  
Author(s):  
Chakib El-Moatassim ◽  
Nicole Bernad ◽  
Jean-Claude Mani ◽  
Jacques Dornand
Keyword(s):  
Purinergic Receptors ◽  
Plasma Membranes ◽  
Divalent Cations ◽  
Extracellular Atp ◽  
Active Species ◽  
Extracellular Nucleotides ◽  
Dependent Manner ◽  
Specific Receptors ◽  
Atp Analogs ◽  
Dose Dependent

We have previously demonstrated that extracellular ATP can give medullary thymocytes the calcium message required for the induction of their blastogenesis, without mobilization of intracellular calcium. We describe here the effects of extracellular nucleotides on membrane permeability to monovalent and divalent cations in mouse thymocytes. Among all nucleotides tested, under physiological conditions, only ATP and, to a lesser extent, 2-methylthio-ATP, adenosine 5′-O-(3-thio-triphosphate), and ADP were able to depolarize thymocyte plasma membranes and to induce Na+ and Ca2+ influxes into thymocytes; other nonhydrolysable ATP analogs were only effective in the absence of Mg2+. The ATP-induced effects were inhibited in a dose-dependent manner by Mg2+ and greatly potentiated in its absence, which suggests that the tetrabasic ATP4− is probably the active species and that a phosphotransferase activity is not involved in its effects. These ATP-mediated changes in ion fluxes result from an increase in nonspecific permeability of thymocyte membranes, probably by pore formation. These ion flux changes might be responsible for the mitogenic induction of phorbol 12-myristate 13-acetate treated medullary thymocytes. The potency order for the adenine derivatives to affect these fluxes (ATP>ADP> >AMP>adenosine) suggests the presence of ATP specific receptors (P2 purinergic receptors) on thymocyte plasma membranes.Key words: purinergic receptors, extracellular ATP, membrane potential, cation fluxes, thymocytes.

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.

scholarly journals Intracellular distribution of haem after uptake by different receptors. Haem-haemopexin and haem-asialo-haemopexin

1985 ◽  
Vol 231 (3) ◽  
pp. 663-669 ◽  
Author(s):  
A Smith
Keyword(s):  
Plasma Membranes ◽  
Colloidal Silica ◽  
Metabolic Fate ◽  
Specific Receptor ◽  
Binding Studies ◽  
Specific Receptors ◽  
Haem Proteins ◽  
Haem Iron

How the interaction of haemopexin with two different receptors affects its subsequent metabolism and ‘intracellular’ haem transport was examined by using mesohaem-haemopexin and mesohaem-asialo-haemopexin. The physical properties of the two haem proteins, including their absorption and c.d. spectra, are similar. Binding studies in vitro showed that haem-asialo-haemopexin interacts with both the haemopexin-specific and galactose-specific receptors on liver plasma membranes, but that haem-haemopexin interacts only with the haemopexin receptor. In vivo haem-asialo-haemopexin rapidly interacts with the liver via the galactose-specific receptor, since the protein is extensively catabolized and uptake is blocked by asialofetuin. Haem iron from haem-asialo-haemopexin is not accumulated in the liver to the same extent as from intact haem-haemopexin, and the native sialylated protein is not proteolysed. Moreover, after fractionation of homogenized liver by using colloidal-silica gradients, liver-associated haem-haemopexin and haem-asialo-haemopexin produced distinctly different patterns for both protein and ligand, consistent with their uptake by two distinct receptors. These results demonstrate that the interaction of haemopexin with different receptors influences its subsequent metabolic fate and that haem iron from haem-haemopexin is efficiently conserved only if it enters the liver cell via the specific haemopexin receptor.

scholarly journals Human and rat mesangial cell receptors for glucose-modified proteins: potential role in kidney tissue remodelling and diabetic nephropathy.

1991 ◽  
Vol 174 (4) ◽  
pp. 931-939 ◽  
Author(s):  
E Y Skolnik ◽  
Z Yang ◽  
Z Makita ◽  
S Radoff ◽  
M Kirstein ◽  
...  
Keyword(s):  
Potential Role ◽  
Mesangial Cells ◽  
Kidney Tissue ◽  
Matrix Proteins ◽  
Tissue Remodelling ◽  
Enhanced Production ◽  
Patients With Diabetes ◽  
Specific Receptors ◽  
Modified Proteins

Advanced glycosylation endproducts (AGEs) are derived from the nonenzymatic addition of glucose to proteins. AGEs have been found to accumulate on tissue proteins in patients with diabetes, and their accumulation is thought to play a role in the development of diabetic complications. The finding that macrophages and endothelial cells contain AGE-specific receptors led us to examine whether mesangial cells (MCs) also possess a mechanism for recognizing and processing AGEs. Membrane extracts isolated from rat and human MCs were found to bind AGE-bovine serum albumin (BSA) in a saturable fashion, with a binding affinity of 2.0 +/- 0.4 x 10(6) M-1 (500 nM). The binding was specific for the AGE adduct, since AGE-modified collagen I and ribonuclease both competitively inhibited 125I-AGE-BSA binding to MC membranes, while the unmodified proteins did not compete. Binding of AGE proteins was followed by slow internalization and degradation of the ligand. Ligand blotting of MC membrane extracts demonstrated three distinct AGE-binding membrane proteins of 50, 40, and 30 kD. Growth of MCs on various AGE-modified matrix proteins resulted in alterations in MC function, as demonstrated by enhanced production of fibronectin and decreased proliferation. These results point to the potential role that the interaction of AGE-modified proteins with MCs may play in vivo in promoting diabetic kidney disease.

Interactions of Malondialdehyde and 4-Hydroxynonenal with Rat Liver Plasma Membranes and their Effect on Binding of Prostaglandin E2by Specific Receptors

1996 ◽  
Vol 25 (5) ◽  
pp. 415-420 ◽  
Author(s):  
Vyacheslav U. Buko ◽  
Alexander Artsukevich ◽  
Iliya Zavodnik ◽  
Alexander Maltsev ◽  
Ljubov Sushko ◽  
...  
Keyword(s):  
Rat Liver ◽  
Plasma Membranes ◽  
Liver Plasma Membranes ◽  
Rat Liver Plasma Membranes ◽  
Specific Receptors

scholarly journals Role of the sialophorin (CD43) receptor in mediating influenza A virus- induced polymorphonuclear leukocyte dysfunction

Blood ◽  
1995 ◽  
Vol 85 (6) ◽  
pp. 1615-1619 ◽  
Author(s):  
JS Abramson ◽  
HR Hudnor
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Plasma Membranes ◽  
Cell Function ◽  
Igg Antibody ◽  
Significant Depression ◽  
Equivalent Control ◽  
Specific Receptors ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony

Polymorphonuclear leukocytes (PMNLs) exposed to influenza A virus (IAV) undergo activation of the respiratory burst followed by depression of cell function when subsequently exposed to particulate or soluble stimuli. The effect of IAV on PMNLs is likely to be mediated through the attachment of IAV to one or more specific receptors. Recently, IAV has been shown to bind to the sialophorin protein (CD43) receptor on PMNL plasma membranes. The present study was performed to determine if the sialophorin receptor was responsible for IAV-induced PMNL dysfunction. When PMNLs were incubated with IAV or CD43 monoclonal antibody (MoAb) for 30 minutes and then exposed to a secondary particulate (opsonized zymosan) or soluble (FMLP or phorbol 12- myristate 13-acetate) stimulus, there was significant depression of the PMNL chemiluminescence response compared with the equivalent control (P < .05). When PMNL were incubated with the CD43 MoAb and then cross- linked with a goat antimouse IgG antibody, no depression of PMNL function occurred upon secondary stimulation. Exposure of cells to IAV aggregates also eliminated the PMNL dysfunction that normally occurs due to the virus. Similar to IAV, PMNL dysfunction due to the CD43 MoAb could be overcome by priming the cells with granulocyte-macrophage colony-stimulating factor. These findings indicate that IAV-induced PMNL dysfunction is mediated, at least in part, through the sialophorin receptor.

Presence of aldosterone-like immunoreactivity in cerebrospinal fluid in normotensive subjects

1992 ◽  
Vol 126 (6) ◽  
pp. 501-504 ◽  
Author(s):  
Yo Kageyama ◽  
Hiromichi Suzuki ◽  
Takao Saruta
Keyword(s):  
Cerebrospinal Fluid ◽  
Potential Role ◽  
Physiological Role ◽  
Plasma Renin ◽  
Wide Distribution ◽  
The Central Nervous System ◽  
Specific Receptors ◽  
Normotensive Subjects ◽  
The Brain

Accumulating evidence, including a wide distribution of specific receptors for aldosterone in the brain, has revealed a potential role of aldosterone in the central nervous system. However, whether or not aldosterone is present in cerebrospinal fluid remains unclear. We attempted to detect aldosterone in cerebrospinal fluid in 14 normotensive subjects. Cerebrospinal fluid was obtained by lumbar puncture. Aldosterone-like immunoreactivity was detected in cerebrospinal fluid (163±5 pmol/l, range 139-211 pmol/l) and was found to significantly correlate to both plasma aldosterone (r = 0.70, p<0.01) and plasma renin activity (r=0.68, p<0.01). However, no significant relationship was found between aldosterone-like immunoreactivity in cerebrospinal fluid and the level of sodium or potassium in cerebrospinal fluid or mean blood pressure. Although we confirmed the presence of aldosterone-like immunoreactivity in cerebrospinal fluid of normotensive subjects, the physiological role of aldosterone in cerebrospinal fluid has yet to be elucidated. Further study will thus be needed to determine the role of cerebrospinal fluid aldosterone.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

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