Interaction of calcium ions and salivary acidic proline-rich proteins with hydroxyapatite. A possible aspect of inhibition of hydroxyapatite formation

The relationship between Ca2+- and hydroxyapatite-binding sites in salivary acidic proline-rich phosphoproteins A and C was investigated. Coating of hydroxyapatite with protein before adsorption had no effect on Ca2+ binding to the mineral, but simultaneous adsorption of Ca+ and protein to hydroxyapatite caused additional Ca2+ binding to the solid. The additional amount of Ca2+ adsorbed, measured in mol of Ca2+/mol of protein adsorbed to hydroxyapatite, was approx. 2 for protein C, 4 for protein A, 9 for the N-terminal tryptic peptide and 2 for dephosphorylated protein A. It is suggested that the ability of the proteins to inhibit hydroxyapatite formation is related to the binding of the proteins to crystal growth sites on the mineral, which prevents access of Ca2+ from the surrounding liquid.

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Calcium binding in cardiac sarcolemma

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y79-080 ◽

1979 ◽

Vol 57 (5) ◽

pp. 529-534 ◽

Cited By ~ 10

Author(s):

N. C. Morcos ◽

A. L. Jacobson

Keyword(s):

Calcium Ions ◽

Binding Sites ◽

Calcium Binding ◽

Total Calcium ◽

Cardiac Sarcolemma ◽

Binding Process ◽

Calcium Binding Sites ◽

Main Factors ◽

High Concentrations ◽

The Relationship

The relationship between calcium binding and ATPase activity has been investigated for guinea pig cardiac sarcolemma. The concentrations of calcium ions and of ATP were the main factors in determining the amount of calcium bound. With a saturating concentration of ATP, at low calcium concentrations (0.1 mM) more than 50% of the total calcium bound was ATP dependent while at high concentrations of calcium (10 mM) only 20% of the calcium bound was ATP dependent. The ATP-dependent calcium binding process involves one class of calcium binding sites while the non-ATP-dependent calcium binding process involves two classes of binding sites.Inhibitor studies of Ca2+-stimulated MgATPase, MgATPase, and CaATPase activities suggest Ca2+ and Mg2+ are either interacting with different sites on the same enzyme or with different enzymes.

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The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100085484 ◽

1991 ◽

Vol 49 ◽

pp. 236-237

Author(s):

J.R. Pfeiffer ◽

J.C. Seagrave ◽

C. Wofsy ◽

J.M. Oliver

Keyword(s):

Mast Cells ◽

Protein A ◽

Scattered Electron ◽

Ige Receptor ◽

Receptor Complexes ◽

Ige Binding ◽

Electron Imaging ◽

Small Clusters ◽

Relationship Of ◽

The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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High Affinity Binding Sites for Activated Protein C and Protein C on Cultured Human Umbilical Vein Endothelial Cells

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648890 ◽

1994 ◽

Vol 72 (03) ◽

pp. 465-474 ◽

Cited By ~ 20

Author(s):

Neelesh Bangalore ◽

William N Drohan ◽

Carolyn L Orthner

Keyword(s):

Binding Sites ◽

Protein C ◽

Umbilical Vein ◽

Activated Protein C ◽

Affinity Binding ◽

Cell Binding ◽

High Affinity Binding ◽

High Affinity ◽

Gla Domain ◽

Umbilical Vein Endothelial Cells

SummaryActivated protein C (APC) is an antithrombotic serine proteinase having anticoagulant, profibrinolytic and anti-inflammatory activities. Despite its potential clinical utility, relatively little is known about its clearance mechanisms. In the present study we have characterized the interaction of APC and its active site blocked forms with human umbilical vein endothelial cells (HUVEC). At 4° C 125I-APC bound to HUVEC in a specific, time dependent, saturable and reversible manner. Scatchard analysis of the binding isotherm demonstrated a Kd value of 6.8 nM and total number of binding sites per cell of 359,000. Similar binding isotherms were obtained using radiolabeled protein C (PC) zymogen as well as D-phe-pro-arg-chloromethylketone (PPACK) inhibited APC indicating that a functional active site was not required. Competition studies showed that the binding of APC, PPACK-APC and PC were mutually exclusive suggesting that they bound to the same site(s). Proteolytic removal of the N-terminal γ-carboxyglutamic acid (gla) domain of PC abolished its ability to compete indicating that the gla-domain was essential for cell binding. Surprisingly, APC binding to these cells appeared to be independent of protein S, a cofactor of APC generally thought to be required for its high affinity binding to cell surfaces. The identity of the cell binding site(s), for the most part, appeared to be distinct from other known APC ligands which are associated with cell membranes or extracellular matrix including phospholipid, thrombomodulin, factor V, plasminogen activator inhibitor type 1 (PAI-1) and heparin. Pretreatment of HUVEC with antifactor VIII antibody caused partial inhibition of 125I-APC binding indicating that factor VIII or a homolog accounted for ∼30% of APC binding. Studies of the properties of surface bound 125I-APC or 125I-PC and their fate at 4°C compared to 37 °C were consistent with association of ∼25% of the initially bound radioligand with an endocytic receptor. However, most of the radioligand appeared not to be bound to an endocytic receptor and dissociated rapidly at 37° C in an intact and functional state. These data indicate the presence of specific, high affinity binding sites for APC and PC on the surface of HUVEC. While a minor proportion of binding sites may be involved in endocytosis, the identity and function of the major proportion is presently unknown. It is speculated that this putative receptor may be a further mechanisms of localizing the PC antithrombotic system to the vascular endothelium.

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USING TEM TO HELP UNDERSTAND THE RELATIONSHIP BETWEEN ARAGONITIC CRYSTAL GROWTH AND ORGANIC COMPOUNDS

10.1130/abs/2016am-287238 ◽

2016 ◽

Author(s):

Maurice P. Testa ◽

◽

Brenda L. Kirkland

Keyword(s):

Crystal Growth ◽

Organic Compounds ◽

The Relationship

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A Pilot Study of the Clinical Relevance of the Relationship between the Serum Level of Pregnancy-Associated Plasma Protein a and the Degree of Acute Coronary Syndrome

Journal of International Medical Research ◽

10.1177/147323001003800225 ◽

2010 ◽

Vol 38 (2) ◽

pp. 625-632 ◽

Cited By ~ 8

Author(s):

L You ◽

L Li ◽

F Zhang ◽

Q Xu ◽

J Ren

Keyword(s):

Acute Coronary Syndrome ◽

Pilot Study ◽

Serum Level ◽

Plasma Protein ◽

Clinical Relevance ◽

Protein A ◽

Coronary Syndrome ◽

The Relationship

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Substitution of lanthanide ions for calcium ions in the activation of bovine prothrombin by activated factor X. High affinity metal-binding sites of prothrombin and the derivatives of prothrombin activation.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)33428-2 ◽

1976 ◽

Vol 251 (11) ◽

pp. 3235-3241

Author(s):

B C Furie ◽

K G Mann ◽

B Furie

Keyword(s):

Calcium Ions ◽

Metal Binding ◽

Binding Sites ◽

Lanthanide Ions ◽

Factor X ◽

Metal Binding Sites ◽

High Affinity ◽

Derivatives Of ◽

Prothrombin Activation

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Prediction of genome-wide effects of single nucleotide variants on transcription factor binding

Scientific Reports ◽

10.1038/s41598-020-74793-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Sebastian Carrasco Pro ◽

Katia Bulekova ◽

Brian Gregor ◽

Adam Labadorf ◽

Juan Ignacio Fuxman Bass

Keyword(s):

Binding Sites ◽

Cancer Type ◽

Single Nucleotide Variants ◽

Single Nucleotide ◽

Regulatory Regions ◽

Genome Wide ◽

Transcriptional Regulatory ◽

Gene Regulatory ◽

The Impact ◽

The Relationship

Abstract Single nucleotide variants (SNVs) located in transcriptional regulatory regions can result in gene expression changes that lead to adaptive or detrimental phenotypic outcomes. Here, we predict gain or loss of binding sites for 741 transcription factors (TFs) across the human genome. We calculated ‘gainability’ and ‘disruptability’ scores for each TF that represent the likelihood of binding sites being created or disrupted, respectively. We found that functional cis-eQTL SNVs are more likely to alter TF binding sites than rare SNVs in the human population. In addition, we show that cancer somatic mutations have different effects on TF binding sites from different TF families on a cancer-type basis. Finally, we discuss the relationship between these results and cancer mutational signatures. Altogether, we provide a blueprint to study the impact of SNVs derived from genetic variation or disease association on TF binding to gene regulatory regions.

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Movement of Calcium Ions and their Role in the Activation of Platelets

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648654 ◽

1978 ◽

Vol 40 (02) ◽

pp. 212-218 ◽

Cited By ~ 60

Author(s):

P Massini ◽

R Käser-Glanzmann ◽

E F Lüscher

Keyword(s):

Plasma Membrane ◽

Platelet Activation ◽

Calcium Ions ◽

Binding Sites ◽

Shape Change ◽

Release Reaction ◽

Dense Bodies ◽

Activated Platelets ◽

Different Types ◽

Ca Ions

SummaryThe increase of the cytoplasmic Ca-concentration plays a central role in the initiation of platelet activation. Four kinds of movements of Ca-ions are presumed to occur during this process: a) Ca-ions liberated from membranes induce the rapid shape change, b) Vesicular organelles release Ca-ions into the cytoplasm which initiate the release reaction, c) The storage organelles called dense bodies, secrete their contents including Ca-ions to the outside during the release reaction, d) At the same time a rearrangement of the plasma membrane occurs, resulting in an increase in its permeability for Ca-ions as well as in an increase in the number of Ca-binding sites.Since most processes occurring during platelet activation are reversible, the platelet must be equipped with a mechanism which removes Ca-ions from the cytoplasm. A vesicular fraction obtained from homogenized platelets indeed accumulates Ca actively. This Ca- pump is stimulated by cyclic AMP and protein kinase; it may be involved in the recovery of platelets after activation.It becomes increasingly clear that the various manifestations of platelet activation are triggered by a rise in the cytoplasmic Ca2+-concentration. The evidence for this and possible mechanisms involved are discussed in some detail in the contributions by Detwiler et al. and by Gerrard and White to this symposium. In this article we shall discuss four different types of mobilization of Ca-ions which occur in the course of the activation of platelets. In addition, at least one transport step involved in the removal of Ca2+ must occur during relaxation of activated platelets.

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