Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The binding of calcium ions by erythrocytes and 'ghost' -cell membranes.

ABSTRACT: 1. Washed human erythrocytes, suspended in iso-osmotic sucrose containing 2.5mm-calcium chloride, bind about 400mug-atoms of calcium/litre of packed cells. Sucrose may be replaced by other sugars. 2. Partial replacement of sucrose by iso-osmotic potassium chloride diminishes the uptake of calcium, 50% inhibition occurring at about 50mm-potassium chloride. 3. Other univalent cations behave like potassium, whereas bivalent cations are much more inhibitory. The tervalent cations, yttrium and lanthanum, however, are the most effective inhibitors of calcium uptake. 4. An approximate correlation exists between the calcium uptake and the sialic acid content of erythrocytes of various species and of human erythrocytes that have been partially depleted of sialic acid by treatment with neuraminidase. However, even after complete removal of sialic acid, human erythrocytes still bind about 140mug-atoms of calcium/litre of packed cells. 5. A Scatchard (1949) plot of calcium uptake at various Ca(2+) concentrations in the suspending media shows the presence of three different binding sites on the external surface of the human erythrocyte membrane. 6. Erythrocyte ;ghost' cells, the membranes of which appear to be permeable to Ca(2+) ions, can bind about 1000mug-atoms of calcium per ;ghost'-cell equivalent of 1 litre of packed erythrocytes. This indicates that there are also binding sites for calcium on the internal surface of the erythrocyte membrane.

SUBMITTER: Long C

PROVIDER: S-EPMC1177083 | biostudies-other | 1971 Aug

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Calcium ions and cell fusion. Effects of chemical fusogens on the permeability of erythrocytes to calcium and other ions.

Project description:1. Fusogenic and non-fusogenic chemicals were tesetd for their ability to allow 45Ca2+ and 3H2O to enter hen and human erythrocytes. 2. The ratio of 45Ca2+/3H2O in treated cells to that in untreated cells is referred to as the entry ratio. 3. Within 1 min at 37 degrees C both water-soluble and lipid-soluble fusogens increased the value of the entry ratio, which reached maximum values in 5--10 min. 4. Values of the entry ratio in the range of 4--12 were found under conditions that led to cell fusion. 5. Closely related but non-fusogenic chemicals did not significantly alter the entry ratio. 6. The entry ratios for 86Rb+, 22Na+ and 35SO42- were also significantly increased by both lipid-soluble and water-soluble fusogens, though the increases were not as large as those for 45Ca2+. 7. It is suggested that fusogenic compounds increase the permeability of biological membranes to ions, and that an increase in the concentration of intracellular Ca2+ initiates or facilitates events that lead to the chemically induced fusion of erythrocytes.

| S-EPMC1161337 | biostudies-other

Dimerization of peptides by calcium ions: investigation of a calcium-binding motif.

Project description:We investigated calcium-binding motifs of peptides and their recognition of active functionalities for coordination. This investigation generates the fundamentals to design carrier material for calcium-bound peptide-peptide interactions. Interactions of different peptides with active calcium domains were investigated. Evaluation of selectivity was performed by electrospray ionization mass spectrometry by infusing solutions containing two different peptides (P1 and P2) in the presence of calcium ions. In addition to signals for monomer species, intense dimer signals are observed for the heterodimer ions (P1 ? Ca(2+) ? P2) (? represents the noncovalent binding of calcium with the peptide) in the positive ion mode and for ions ([P1-2H](2-) ? Ca(2+) ? [P2-2H](2-)) in the negative ion mode. Monitoring of the dissociation from these mass selected dimer ions via the kinetic method provides information on the calcium affinity order of different peptide sequences.

| S-EPMC4177772 | biostudies-literature

The influx of calcium ions into human erythrocytes during cold storage.

Project description:1. When human erythrocytes, suspended in iso-osmotic sucrose containing CaCl(2), are stored at 3 degrees C, Ca(2+) influx into the cells occurs. Simultaneously, efflux of K(+), Na(+), Cl(-) and water takes place and cell volume diminishes. 2. The extent of Ca(2+) influx increases with duration of cold storage and with increasing concentration of Ca(2+) in the suspending medium. 3. Erythrocytes that have been thus loaded with Ca(2+) exhibit Ca(2+) efflux against a concentration gradient when subsequently incubated at 37 degrees C. 4. Ca(2+) influx likewise occurs when the sucrose of the medium is replaced by iso-osmotic solutions of other non-ionized compounds. 5. Replacement of sucrose by iso-osmotic KCl or NaCl greatly diminishes the rate of Ca(2+) influx during cold storage; however, in iso-osmotic choline chloride, Ca(2+) influx is as rapid as in sucrose. 6. Preincubation of erythrocytes in iso-osmotic sucrose at 37 degrees C causes rapid efflux of K(+) and Na(+) and renders the cell membranes highly permeable to Ca(2+) during subsequent cold storage. 7. Preincubation of erythrocytes in iso-osmotic NaCl at 37 degrees C with trypsin or neuraminidase is without effect on the permeability of the membrane towards Ca(2+). 8. The experimental results lead to the conclusion that the main prerequisite for Ca(2+) influx into erythrocytes is the partial depletion of the cells of their univalent cations.

| S-EPMC1177621 | biostudies-other

Calcium binding by human erythrocyte membranes.

Project description:1. The characteristics of Ca(2+) binding to haemoglobin-free human erythrocyte membranes were investigated by using (45)Ca and centrifugation partition of ;ghosts' from their external incubation medium. Equilibrium of ;ghosts' with external Ca(2+) required less than 15min. 2. The binding did not vary with temperature in the range 0-37 degrees C. 3. At pH7.4 ;ghosts' bound a maximum of 283mumol of Ca(2+)/g of ;ghost' protein, equivalent to 6.85x10(7) Ca(2+) ions per cell. 4. Increasing the ionic strength from 0.01 to 0.46 diminished Ca(2+) binding, as did ATP in concentrations ranging from 0 to 15mm in the incubation medium. 5. An increase of the pH from 3.0 to 9.3 caused a marked increase in the amount of Ca(2+) bound. 6. Extraction of (45)Ca-labelled ;ghosts' with chloroform-methanol showed that the distribution of Ca(2+) was: 79% protein-bound, 16% lipid-bound, 5% in the aqueous phase, presumably non-bound. Most of the lipid-bound Ca(2+) (about 80%) was associated with a phospholipid fraction containing phosphatidylserine, phosphoinositides and phosphatidylethanolamine, giving a molar Ca(2+): phosphorus ratio of about 1:2.

| S-EPMC1177226 | biostudies-other

Electropermeabilization of Inner and Outer Cell Membranes with Microsecond Pulsed Electric Fields: Quantitative Study with Calcium Ions.

Project description:Microsecond pulsed electric fields (?sPEF) permeabilize the plasma membrane (PM) and are widely used in research, medicine and biotechnology. For internal membranes permeabilization, nanosecond pulsed electric fields (nsPEF) are applied but this technology is complex to use. Here we report that the endoplasmic reticulum (ER) membrane can also be electropermeabilized by one 100 µs pulse without affecting the cell viability. Indeed, using Ca2+ as a permeabilization marker, we observed cytosolic Ca2+ peaks in two different cell types after one 100 µs pulse in a medium without Ca2+. Thapsigargin abolished these Ca2+ peaks demonstrating that the calcium is released from the ER. Moreover, IP3R and RyR inhibitors did not modify these peaks showing that they are due to the electropermeabilization of the ER membrane and not to ER Ca2+ channels activation. Finally, the comparison of the two cell types suggests that the PM and the ER permeabilization thresholds are affected by the sizes of the cell and the ER. In conclusion, this study demonstrates that µsPEF, which are easier to control than nsPEF, can permeabilize internal membranes. Besides, ?sPEF interaction with either the PM or ER, can be an efficient tool to modulate the cytosolic calcium concentration and study Ca2+ roles in cell physiology.

| S-EPMC5638809 | biostudies-other

Single-molecule force spectroscopy reveals force-enhanced binding of calcium ions by gelsolin.

Project description:Force is increasingly recognized as an important element in controlling biological processes. Forces can deform native protein conformations leading to protein-specific effects. Protein-protein binding affinities may be decreased, or novel protein-protein interaction sites may be revealed, on mechanically stressing one or more components. Here we demonstrate that the calcium-binding affinity of the sixth domain of the actin-binding protein gelsolin (G6) can be enhanced by mechanical force. Our kinetic model suggests that the calcium-binding affinity of G6 increases exponentially with force, up to the point of G6 unfolding. This implies that gelsolin may be activated at lower calcium ion levels when subjected to tensile forces. The demonstration that cation-protein binding affinities can be force-dependent provides a new understanding of the complex behaviour of cation-regulated proteins in stressful cellular environments, such as those found in the cytoskeleton-rich leading edge and at cell adhesions.

| S-EPMC4143929 | biostudies-literature

CcbP, a calcium-binding protein from Anabaena sp. PCC 7120, provides evidence that calcium ions regulate heterocyst differentiation.

Project description:Although it is known that calcium is a very important messenger involved in many eukaryotic cellular processes, much less is known about calcium's role in bacteria. CcbP, a Ca(2+)-binding protein, was isolated from the heterocystous cyanobacterium Anabaena sp. PCC 7120, and the ccbP gene was cloned and inactivated. In the absence of combined nitrogen, inactivation of ccbP resulted in multiple contiguous heterocysts, whereas overexpression of ccbP suppressed heterocyst formation. Calmodulin, which is not present in Anabaena species, could also suppress heterocyst formation in both Anabaena sp. PCC 7120 and Anabaena variabilis. HetR induction upon nitrogen step-down was slow in the strain overexpressing ccbP. The Ca(2+) reporter protein obelin was used to show that mature heterocysts had a high intracellular free Ca(2+)concentration {[Ca(2+)](i)}, and immunoblotting showed that CcbP was absent from heterocysts. A regular pattern of cells with higher [Ca(2+)](i) was established during heterocyst differentiation before the appearance of proheterocysts. A rapid increase of [Ca(2+)](i) could be detected 4 h after the removal of combined nitrogen, and this increase was suppressed by excessive CcbP. These results suggest that Ca(2+) ions play very important roles in hetR induction and heterocyst differentiation.

| S-EPMC556313 | biostudies-literature

Comparative Analysis Between Dentinogenic Ghost Cell Tumor and Ghost Cell Odontogenic Carcinoma: A Systematic Review.

Project description:Dentinogenic ghost cell tumor (DGCT) and ghost cell odontogenic carcinoma (GCOC) form a spectrum of rare benign and malignant odontogenic neoplasms, respectively. The aim of this study was to perform a comparative systematic review of the clinicopathological, genetic, therapeutic, and prognostic features of DGCT and GCOC. The electronic search was performed until December 2020 on seven electronic databases. Case reports, series, and research studies with enough histopathological criteria for diagnosis and all genomic studies were included. Both DGCT and GCOC showed a male prevalence (p = 0.043), with mandibular and maxillary predilections, respectively (p = 0.008). Peripheral DGCT (DGCTp) affected most elderly people (p < 0.001), and central DGCT (DGCTc) and GCOC occurred mainly in younger individuals. Unilateral enlargement of maxilla or mandible was the most common clinical sign associated with a radiolucent or mixed image. Ameloblastomatous epithelium was often present in both neoplasms. Basaloid and large cells with vesicular nuclei were also frequently seen in GCOC. β-catenin expression and mutations (CTNNB1 gene) were found in DGCT and GCOC. Conservative surgery was mostly used for DGCTp, while radical resection was chosen for DGCTc and GCOC. High recurrence rates were found in DGCTc and GCOC. Metastasis occurred in 16.7% of GCOC cases and the 5-year survival rate was 72.6%. DGCT and GCOC share numerous clinicopathological features and demand a careful histopathological evaluation, considering the overlap features with other odontogenic tumors and the possibility of malignant transformation of DGCT. A strict regular post-operative follow-up is mandatory due to high recurrence rates and metastatic capacity in GCOC.

| S-EPMC8633206 | biostudies-literature

Binding of calcium ions and SNAP-25 to the hexa EF-hand protein secretagogin.

Project description:Secretagogin is a hexa EF-hand protein, which has been identified as a novel potential tumour marker. In the present study, we show that secretagogin binds four Ca2+ ions (log K1=7.1+/-0.4, log K2=4.7+/-0.6, log K3=3.6+/-0.7 and log K4=4.6+/-0.6 in physiological salt buffers) with a [Ca2+](0.5) of approx. 25 microM. The tertiary structure of secretagogin changes significantly upon Ca2+ binding, but not upon Mg2+ binding, and the amount of exposed hydrophobic surface in secretagogin increases upon Ca2+ binding, but not upon Mg2+ binding. These properties suggest that secretagogin belongs to the 'sensor' family of Ca2+-binding proteins. However, in contrast with the prototypical Ca2+ sensor calmodulin, which interacts with a very large number of proteins, secretagogin is significantly less promiscuous. Only one secretagogin-interacting protein was reproducibly identified from insulinoma cell lysates and from bovine and mouse brain homogenates. This protein was identified as SNAP-25 (25 kDa synaptosome-associated protein), a protein involved in Ca2+-induced exocytosis in neurons and in neuroendocrine cells. K(d) was determined to be 1.2x10(-7) M in the presence of Ca2+ and 1.5x10(-6) M in the absence of Ca2+. The comparatively low Ca2+ affinity for secretagogin and the fact that it undergoes Ca2+-induced conformational changes and interacts with SNAP-25 raise the possibility that secretagogin may link Ca2+ signalling to exocytotic processes.

| S-EPMC1698678 | biostudies-literature

Primary role of calcium ions in arachidonic acid release from rat platelet membranes. Comparison with human platelet membranes.

Project description:The liberation of arachidonic acid (AA) was investigated in platelet membranes prelabelled with [3H]AA. In rat platelet membranes, Ca2+ at concentrations over several hundred nanomolar induced [3H]AA release, with a concurrent decrease in 3H radioactivity of phosphatidylethanolamine and phosphatidylcholine. Some 4-6% of total radioactivity incorporated into platelet membrane lipids was released at 1-10 microM-Ca2+, which is nearly equivalent to that attained in agonist-stimulated platelets. Formation of lysophospholipids in [3H]glycerol-labelled membranes and decrease in [3H]AA liberated by the phospholipase A2 inhibitors mepacrine and ONO-RS-082 suggest that [3H]AA release is mainly catalysed by phospholipase A2. In intact platelets agonist-stimulated [3H]AA release was markedly decreased in the absence of extracellular Ca2+ or in the presence of the intracellular Ca2+ chelator quin 2. These results indicate that in rat platelets the rise of intracellular Ca2+ plays a primary role in the activation of phospholipase A2. In contrast, Ca2+ even at high millimolar concentrations did not effectively stimulate [3H]AA release in human platelet membranes. Thus factor(s) additional to or independent of Ca2+ is required for the liberation of AA in human platelets.

| S-EPMC1138483 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data