Large-scale isolation of human erythrocyte Ca2+-transport ATPase.
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ABSTRACT:
SUBMITTER: Gietzen K
PROVIDER: S-EPMC1153836 | biostudies-other | 1982 Oct
REPOSITORIES: biostudies-other
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Project description:Coefficients for active transport of ions and heat in vesicles with Ca(2+)-ATPase from sarcoplasmic reticulum are defined in terms of a newly proposed thermodynamic theory and calculated using experiments reported in the literature. The coefficients characterize in a quantitative manner different performances of the enzyme isoforms. Four enzyme isoforms are examined, namely from white and red muscle tissue, from blood platelets, and from brown adipose mitochondria. The results indicate that the isoforms have a somewhat specialized function. White muscle tissue and brown adipose tissue have the same active transport coefficient ratio, but the activity level of the enzyme in white muscle is higher than in brown adipose tissue. The thermogenesis ratio is high in both white muscle and brown adipose tissue, in agreement with a specific role in nonshivering thermogenesis. Other isoforms do not have this ability to generate heat. A calcium-dependence of the coefficients is found, which can be understood as being in accordance with the role of this ion as a messenger in muscle contraction as well as in thermogenesis. The investigation points to new experiments related to structure as well as to function of the isoforms.
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Project description:Antibodies against purified Ca2+-transport ATPase from human erythrocytes were raised in rabbits. Immunodiffusion experiments revealed that precipitating antibodies had been developed. The immunoglobulin fraction inhibited solely the calmodulin-dependent fraction of erythrocyte Ca2+-transport ATPase activity, whereas the basal (in the absence of added calmodulin) activity of the enzyme was not significantly affected by the antibodies. The antibodies produced similar doseresponse curves for the calmodulin- and the oleic acid-stimulated enzyme. However, the immunoglobulin fraction was considerably less effective in inhibiting Ca2+-transport ATPase activated by limited proteolysis. The results obtained with our antibodies are compatible with the interpretation that at least one subpopulation of the antibodies attacks the enzyme at or close to the calmodulin-binding site of the ATPase. The antibodies also inhibited the calmodulin-regulated Ca2+-transport ATPase from pig smooth-muscle plasma membrane, though with lower potency. However, the immunoglobulin fraction failed to suppress pig cardiac sarcoplasmicreticulum Ca2+-transport ATPase activity in the concentration range investigated. In addition, the activity of phosphodiesterase from rat brain, another enzyme modulated by calmodulin, was not at all affected by the immunoglobulin fraction.
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Project description:Background and objectivesThe human Amniotic epithelial cells (AME) derived from amniotic membrane of placenta have been considered as the potential fetal stem cell source with minimal or no ethical concerns and are important therapeutic tool for anti-fibrotic and regenerative therapies.Methods and resultsHere, we evaluated the isolation, media screening, scale-up and characterization of AME cells. The isolation, expansion of AMEs were performed by sequential passaging and growth kinetics studies. The AMEs were characterized using immunocytochemistry, immunophenotyping, In-vitro differentiation, and anti-fibrotic assays. The growth kinetics study revealed that the AME cultured in Ultraculture (UC) and DMEM knockout (DMEM-KO) have prominently higher growth rate compared to others. Overall, the AMEs cultured from 5 different media retained basic morphological characteristics and the functional characteristics.ConclusionsOur result suggests that the AMEs can be successfully cultured in UC based complete media without losing its epithelial cell characteristics even after passaging for passage 2 (P2). However, a careful and methodical pre-clinical and clinical translation studies need to be conducted to show its safety and efficacy.
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Project description:The Ca2+-pumping ATPase (Ca2+-ATPase) was purified from human and pig erythrocyte membranes by calmodulin affinity chromatography in the presence of phosphatidylcholine. The amount of enzyme present in pig erythrocytes is at least 7 times greater than that isolated from human erythrocyte ghosts. However, the properties of the enzyme from the two species are similar in many respects.
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Project description:A technique is described for the isolation of a plasma membrane-enriched preparation from a rat liver post-mitochondrial fraction by using discontinuous Percoll density-gradient centrifugation. The procedure is simple, of high reproducibility and yield and requires a total isolation time of only 90 min. The preparation consists almost exclusively of membrane vesicles and is enriched approx. 26-fold in plasma membrane-localized enzymes with minor contamination (less than 10%) with membranes derived mainly from the endoplasmic reticulum and Golgi apparatus. Approx. 20% of the fraction comprises tightly-sealed vesicles in the inverted orientation which are capable of accumulating calcium ions and exhibiting vanadate-insensitive Ca2+-ATPase activity. The properties of these activities, including insensitivity to vanadate, oxalate, and to p-chloromercuribenzoate as well as a lack of requirement for added Mg2+, contrast markedly with the reported properties of Ca2+ transport by the endoplasmic reticulum isolated from rat liver. The technique may have wide application in the study of plasma membrane-associated activities in rat liver, particularly in relation to sinusoidal membrane surface-related events.
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Project description:Treatment of extensively washed erythrocyte membranes with 0.1mm-EDTA decreased their Mg(2+)-dependent, Ca(2+)-stimulated ATPase [(Mg(2+)+Ca(2+))-ATPase] activity. An activator released by this treatment restored the (Mg(2+)+Ca(2+))-ATPase to its original value in a Ca(2+)-dependent manner. This activator was different from calmodulin, as determined by a number of criteria. It was retained on an Amicon XM-100 ultrafiltration membrane (molecular-weight cut-off 100000); it appeared in the void volume of Sephadex G-100 and G-75 columns; it was not retained on a DEAE-cellulose ion-exchange column at ionic strengths similar to those used to retain calmodulin; and it maximally activated (Mg(2+)+Ca(2+))-ATPase activity less than calmodulin and at a higher Ca(2+) concentration. Like calmodulin, the activator is heat-stable. The activator fraction isolated on a 2.5-15% sucrose gradient in 0.16m-KCl showed a single band of mol.wt. 63000 and no calmodulin on 10%-polyacrylamide/sodium dodecyl sulphate gels. A trace amount of calmodulin was detected in the activator fraction by radioimmunoassay (approx. 10pg/ml of ;ghosts'), but this amount was insufficient to account for the (Mg(2+)+Ca(2+))-ATPase activation. Furthermore, calmodulin-binding protein failed to inhibit (Mg(2+)+Ca(2+))-ATPase activity by more than 10-20% in the membrane preparations from which the activator was extracted. It was concluded that erythrocyte membranes contain a (Mg(2+)+Ca(2+))-ATPase activator that may attenuate the activation of the Ca(2+)-transport ATPase by calmodulin.
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