Comparison of the pharmacological characteristics of 5 HT1 and 5 HT2 binding sites with those of serotonin autoreceptors which modulate serotonin release

1982 ◽  
Vol 321 (3) ◽  
pp. 165-170 ◽  
Author(s):  
Louis L. Martin ◽  
Elaine Sanders-Bush
Keyword(s):  
Binding Sites ◽  
Serotonin Release ◽  
Serotonin Autoreceptors

scholarly journals Recombinant scinderin, an F-actin severing protein, increases calcium- induced release of serotonin from permeabilized platelets, an effect blocked by two scinderin-derived actin-binding peptides and phosphatidylinositol 4,5-bisphosphate

Blood ◽  
1996 ◽  
Vol 87 (1) ◽  
pp. 20-24
Author(s):  
MG Marcu ◽  
L Zhang ◽  
K Nau-Staudt ◽  
JM Trifaro
Keyword(s):  
Binding Sites ◽  
Chromaffin Cells ◽  
Serotonin Release ◽  
Actin Binding ◽  
Specific Site ◽  
Actin Depolymerization ◽  
Published Evidence ◽  
Vessel Injury ◽  
Binding Peptides ◽  
Shape Changes

In response to vessel injury or exposure to different substances, platelets undergo activation which consists of shape changes, formation of cellular pseudopodia, aggregation, and secretion. These dramatic changes are accompanied by cycles of actin depolymerization and polymerization. Previous work has shown the presence in platelets of gelsolin and scinderin, two Ca(2+)-dependent F-actin severing proteins. Recent published evidence suggests that scinderin is a component of the exocytotic machinery in chromaffin cells. The present work describes the preparation of recombinant scinderin and peptides Sc-ABP1 and Sc-ABP2 with sequences corresponding to two actin-binding sites of scinderin. Recombinant scinderin and peptides Sc-ABP1 and Sc-ABP2 were tested for their effects on Ca(2+)-induced serotonin release from digitonin permeabilized platelets. The results indicated that recombinant scinderin potentiates Ca(2+)-evoked serotonin release, an effect blocked in the presence of Sc-ABP1, Sc-ABP2, exogenous gamma-actin, or the addition of phosphatidylinositol 4,5-bisphosphate (PIP2). In the presence of a mismatched peptide (MMP) the potentiating effect of recombinant scinderin was not affected. Moreover, Sc-ABP1, Sc-ABP2, and gamma-actin inhibited Ca(2+)-induced release of serotonin in the absence of recombinant scinderin, suggesting an inhibition of platelet endogenous scinderin. MMP was ineffective under these conditions. The results suggest that F-actin disassembly, perhaps at a specific site, is required for platelet secretion and that scinderin might be an important component of the exocytotic machinery in platelets.

scholarly journals The binding of human and bovine thrombin to human platelets

Blood ◽  
1976 ◽  
Vol 47 (1) ◽  
pp. 43-54 ◽  
Author(s):  
MA Shuman ◽  
DM Tollefsen ◽  
PW Majerus
Keyword(s):  
Dissociation Constant ◽  
Platelet Function ◽  
Primary Structure ◽  
Binding Sites ◽  
Human Platelets ◽  
Serotonin Release ◽  
Bovine Thrombin ◽  
High Affinity ◽  
Human Thrombin ◽  
Specific Receptors

Abstract Human thrombin binds to specific receptors on the surface of human platelets in a manner analogous to bovine thrombin. Thus, two classes of binding are observed--high affinity with a dissociation constant (Kdiss) of 0.02 U/ml and low affinity with a Kdiss of 5 U/ml. Bovine and human thrombin bind to the same platelet receptors, although bovine thrombin binds with slightly greater affinity. When the amount of thrombin bound to platelets is related to the extent of 14C-serotonin release, bovine and human thrombin are equally effective. Antibodies to human and bovine thrombin were found to differ markedly in their ability to precipitate thrombin of the two species. Thus, antibovine thrombin precipitated eightfold more bovine thrombin than human thrombin, while antihuman thrombin precipitated tenfold more human thrombin than bovine thrombin. Similar differences were found in the ability of Fab fragments of these antibodies to block the interaction of thrombin of each species with human platelets. The finding that both species of thrombin, despite significant evolutionary differences in primary structure, retain essentially identical binding sites to platelets suggests that this part of the thrombin molecule is physiologically important and supports our hypothesis of a role for thrombin binding to platelets in platelet function and hemostasis.

scholarly journals Mathematical Models of Serotonin, Histamine, and Depression

2021 ◽  
Author(s):  
Janet Best ◽  
Anna Marie Buchanan ◽  
Herman Frederik Nijhout ◽  
Parastoo Hashemi ◽  
Michael C. Reed
Keyword(s):  
Mathematical Models ◽  
Serotonin Release ◽  
Experimental Techniques ◽  
Joint Research ◽  
Brain Histamine ◽  
Biological Phenomena ◽  
Serotonin Autoreceptors ◽  
Neuropsychiatric Diseases ◽  
Working Together ◽  
The Brain

The coauthors have been working together for ten years on serotonin, dopamine, and histamine and their connection to neuropsychiatric illnesses. Hashemi has pioneered many new experimental techniques for measuring serotonin and histamine in real time in the extracellular space in the brain. Best, Reed, and Nijhout have been making mathematical models of brain metabolism to help them interpret Hashemi’s data. Hashemi demonstrated that brain histamine inhibits serotonin release, giving a direct mechanism by which inflammation can cause a decrease in brain serotonin and therefore depression. Many new biological phenomena have come out of their joint research including 1) there are two different reuptake mechanisms for serotonin; 2) the effect of the serotonin autoreceptors is not instantaneous and is long-lasting even when the extracellular concentrations have returned to normal; 3) that mathematical models of serotonin metabolism and histamine metabolism can explain Hashemi’s experimental data; 4) that variation in serotonin autoreceptors may be one of the causes of serotonin-linked mood disorders. Here we review our work in recent years for biological audiences, medical audiences, and researchers who work on mathematical modeling of biological problems. We discuss the experimental techniques, the creation and investigation of mathematical models, and the consequences for neuropsychiatric diseases.

scholarly journals The binding of human and bovine thrombin to human platelets

Blood ◽  
1976 ◽  
Vol 47 (1) ◽  
pp. 43-54
Author(s):  
MA Shuman ◽  
DM Tollefsen ◽  
PW Majerus
Keyword(s):  
Dissociation Constant ◽  
Platelet Function ◽  
Primary Structure ◽  
Binding Sites ◽  
Human Platelets ◽  
Serotonin Release ◽  
Bovine Thrombin ◽  
High Affinity ◽  
Human Thrombin ◽  
Specific Receptors

Human thrombin binds to specific receptors on the surface of human platelets in a manner analogous to bovine thrombin. Thus, two classes of binding are observed--high affinity with a dissociation constant (Kdiss) of 0.02 U/ml and low affinity with a Kdiss of 5 U/ml. Bovine and human thrombin bind to the same platelet receptors, although bovine thrombin binds with slightly greater affinity. When the amount of thrombin bound to platelets is related to the extent of 14C-serotonin release, bovine and human thrombin are equally effective. Antibodies to human and bovine thrombin were found to differ markedly in their ability to precipitate thrombin of the two species. Thus, antibovine thrombin precipitated eightfold more bovine thrombin than human thrombin, while antihuman thrombin precipitated tenfold more human thrombin than bovine thrombin. Similar differences were found in the ability of Fab fragments of these antibodies to block the interaction of thrombin of each species with human platelets. The finding that both species of thrombin, despite significant evolutionary differences in primary structure, retain essentially identical binding sites to platelets suggests that this part of the thrombin molecule is physiologically important and supports our hypothesis of a role for thrombin binding to platelets in platelet function and hemostasis.

scholarly journals Characterization of New Monoclonal PF4-Specific Antibodies as Useful Tools for Studies on Typical and Autoimmune Heparin-Induced Thrombocytopenia

2020 ◽  
Author(s):  
Caroline Vayne ◽  
Thi-Huong Nguyen ◽  
Jérôme Rollin ◽  
Noémie Charuel ◽  
Anne Poupon ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Single Molecule ◽  
Binding Sites ◽  
Serotonin Release ◽  
Titration Calorimetry ◽  
Enzyme Linked Immunosorbent Assay ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
Activation Assay ◽  
Group 3

Abstract Background Heparin-induced thrombocytopenia (HIT) is typically caused by platelet-activating immunoglobulin G (IgG) antibodies (Abs) against platelet factor 4 (PF4) complexed with heparin (H). Much less frequent “autoimmune” HIT is distinguished from typical HIT by platelet activation without heparin and the presence of both anti-PF4/H and anti-PF4 IgG. We developed three murine monoclonal anti-PF4 Abs with a human Fc-part, 1E12, 1C12, and 2E1, resembling autoimmune HIT Abs. Objectives To characterize 1E12, 1C12, and 2E1 in comparison to the heparin-dependent monoclonal anti-PF4/H Abs 5B9 and KKO, and polyclonal Abs from patients with typical HIT (group-2) and autoimmune HIT (group-3). Methods Interactions of Abs with PF4 and PF4/H were studied by enzyme-linked-immunosorbent assay, single-molecule force spectroscopy, isothermal titration calorimetry, and dynamic light scattering. Serotonin release assay and heparin-induced platelet activation assay were used to assess platelet activation. The binding sites of monoclonal Abs on PF4 were predicted in silico (MAbTope method). Results 1C12, 1E12, and 2E1 displayed higher affinity for PF4/H complexes than 5B9 and KKO, comparable to human group-3 Abs. Only 1C12, 1E12, 2E1, and group-3 Abs formed large complexes with native PF4, and activated platelets without heparin. The predicted binding sites of 1C12, 1E12, and 2E1 on PF4 differed from those of KKO and 5B9, but were close to each other. 2E1 exhibited unique bivalent binding, involving its antigen recognition site to PF4 and charge-dependent interactions with heparin. Conclusion 1C12, 1E12, and 2E1 are tools for studying the pathophysiology of autoimmune HIT. 2E1 provides evidence for a new binding mechanism of HIT Abs.

scholarly journals Recombinant scinderin, an F-actin severing protein, increases calcium- induced release of serotonin from permeabilized platelets, an effect blocked by two scinderin-derived actin-binding peptides and phosphatidylinositol 4,5-bisphosphate

Blood ◽  
1996 ◽  
Vol 87 (1) ◽  
pp. 20-24 ◽  
Author(s):  
MG Marcu ◽  
L Zhang ◽  
K Nau-Staudt ◽  
JM Trifaro
Keyword(s):  
Binding Sites ◽  
Chromaffin Cells ◽  
Serotonin Release ◽  
Actin Binding ◽  
Specific Site ◽  
Actin Depolymerization ◽  
Published Evidence ◽  
Vessel Injury ◽  
Binding Peptides ◽  
Shape Changes

Abstract In response to vessel injury or exposure to different substances, platelets undergo activation which consists of shape changes, formation of cellular pseudopodia, aggregation, and secretion. These dramatic changes are accompanied by cycles of actin depolymerization and polymerization. Previous work has shown the presence in platelets of gelsolin and scinderin, two Ca(2+)-dependent F-actin severing proteins. Recent published evidence suggests that scinderin is a component of the exocytotic machinery in chromaffin cells. The present work describes the preparation of recombinant scinderin and peptides Sc-ABP1 and Sc-ABP2 with sequences corresponding to two actin-binding sites of scinderin. Recombinant scinderin and peptides Sc-ABP1 and Sc-ABP2 were tested for their effects on Ca(2+)-induced serotonin release from digitonin permeabilized platelets. The results indicated that recombinant scinderin potentiates Ca(2+)-evoked serotonin release, an effect blocked in the presence of Sc-ABP1, Sc-ABP2, exogenous gamma-actin, or the addition of phosphatidylinositol 4,5-bisphosphate (PIP2). In the presence of a mismatched peptide (MMP) the potentiating effect of recombinant scinderin was not affected. Moreover, Sc-ABP1, Sc-ABP2, and gamma-actin inhibited Ca(2+)-induced release of serotonin in the absence of recombinant scinderin, suggesting an inhibition of platelet endogenous scinderin. MMP was ineffective under these conditions. The results suggest that F-actin disassembly, perhaps at a specific site, is required for platelet secretion and that scinderin might be an important component of the exocytotic machinery in platelets.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

Sites of Insulin Action Using Ferritin Labeling

1971 ◽  
Vol 29 ◽  
pp. 540-541
Author(s):  
Burton B. Silver ◽  
Ronald S. Nelson
Keyword(s):  
Electron Microscopy ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Insulin Action ◽  
Diabetic Rats ◽  
Insulin Antibody ◽  
Fat Pad ◽  
Target Organs ◽  
Uranium Salts ◽  
Sugar Levels

Some investigators feel that insulin does not enter cells but exerts its influence in some manner on the cell surface. Ferritin labeling of insulin and insulin antibody was used to determine if binding sites of insulin to specific target organs could be seen with electron microscopy.Alloxanized rats were considered diabetic if blood sugar levels were in excess of 300 mg %. Test reagents included ferritin, ferritin labeled insulin, and ferritin labeled insulin antibody. Target organs examined were were diaphragm, kidney, gastrocnemius, fat pad, liver and anterior pituitary. Reagents were administered through the left common carotid. Survival time was at least one hour in test animals. Tissue incubation studies were also done in normal as well as diabetic rats. Specimens were fixed in gluteraldehyde and osmium followed by staining with lead and uranium salts. Some tissues were not stained.

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