Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9Y573 (actin-binding protein)
 1,734 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Actin, myosin and actin-binding protein have been identified in lymphoid cell lines of Null, B or T type of normal and malignant origin. The cells were fractionated into cytosol (Fraction 1), high KC1 extract (Fraction 2) and mainly membrane (Fraction 3). The distribution of the three contractile proteins and the ATPase activities of myosin and actomyosin in B lymphoblastoid normal and B-lymphoma malignant cell lines. Actomyosin-ATPase activity in the normal B line was much higher than it was in the Null B or T malignant lines examined. These results agree with the assumption that malignant transformation is accompanied by an impairment of the action of contractile proteins that leads to a decrease in motility.
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PMID:Actin, myosin and actin-binding protein in lymphoid cells from human normal and leukemic cell lines. 621 68

The shape change and aggregation of washed platelets induced by 10 microM arachidonic acid (AA) can be reversed by 20 ng/ml prostacyclin (PGI2), but these platelets can be reactivated by treatment with 30 microM epinephrine and subsequent addition of 10 microM AA mixture. These events may be modulated by cAMP since 2 mM dibutyryl cAMP also reversed activation without reactivation by epinephrine and AA. We examined protein phosphorylation and formation of cytoskeletal cores resistant to 1% Triton X-100 extraction of these platelets and correlated these processes with aggregation, fibrinogen binding, and changes in ultrastructure. Unactivated platelet cores contained less than 15% of the total actin and no detectable myosin or actin-binding protein. AA-induced cytoskeletal cores, which contained 60-80% of the total actin, myosin, and actin-binding protein as the major components, were disassembled back to unactivated levels by PGI2 and then fully reassembled by epinephrine and AA. Phosphorylation of myosin light chain and a 40,000-dalton protein triggered by AA (two- to fivefold) was reversed to basal levels by PGI2 but was completely restored to peak levels upon addition of the epinephrine and AA mixture. The reversibility of actin-binding protein phosphorylation could not be established clearly because both PGI2 and dibutyryl cAMP caused its phosphorylation independent of activation. With this possible exception, cytoskeletal assembly with associated protein phosphorylation, aggregation, fibrinogen binding, and changes in ultrastructure triggered by activation are readily and concertedly recyclable.
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PMID:Recycling of platelet phosphorylation and cytoskeletal assembly. 642 49

By using highly purified surface and intracellular membrane fractions prepared from human platelets by free-flow electrophoresis, the polypeptide and glycopeptides of these membranes have been characterized by high-resolution gel electrophoresis under reducing and non-reducing conditions. Silver staining and a variety of glycoprotein-staining procedures have been applied to identify the major components. The principal finding was the clear disparity between the distribution patterns for these two membrane fractions. There are proportionately more low-Mr acidic components present in the intracellular membrane than in the surface-derived membrane. Of the major platelet surface glycoproteins GPIb, IIb, IIIa and IIIb (or IV) well expressed in the surface membrane only, GPIIb and IIIa appear as trace components in the intracellular membrane. The cytoskeleton proteins, actin, myosin, tropomyosin, actin-binding protein and alpha-actinin are prominent features of the surface membrane and essentially absent from the intracellular membrane. Neuraminidase treatment at the whole-cell level, before homogenization, which is an essential requirement for good resolution of the two membrane subfractions, modifies a number of the glycoprotein subunits with respect to their pI characteristics, suggesting much molecular micro-heterogeneity with respect to sialic acid content. A comparison of the staining characteristics of the major glycoproteins with periodic acid/Schiff's reagent and concanavalin A/peroxidase detection and a combined procedure revealed significant differences in associated carbohydrate structures, and the major concanavalin A-binding component was shown to be GPIIIa. These observations are discussed in the context of functional activities of both membrane systems in the physiological behaviour of the platelet.
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PMID:Two-dimensional polyacrylamide-gel electrophoresis of the proteins and glycoproteins of purified human platelet surface and intracellular membranes. 647 8

Incubation of washed rabbit platelets with suspensions of dilauroylglycerophosphocholine resulted in the shedding of vesicles without causing any appreciable leakage of cytoplasmic marker (lactate dehydrogenase) or organelle marker [( 14C]serotonin). The response was dependent on incubation time, concentration of dilauroylglycerophosphocholine and reaction temperature. Vesicles were separated from platelets and exogenous dilauroylglycerophosphocholine by a series of centrifugation steps. An average diameter of vesicles was 100-200 nm on scanning electron microscopy. Vesicles were enriched 5-fold in plasma membrane marker enzyme, acetylcholinesterase, whereas specific activities of lactate dehydrogenase and intracellular membrane marker enzyme, NADH-cytochrome c reductase were decreased in vesicles. Protein analysis by SDS-polyacrylamide gel electrophoresis showed that actin and actin-binding protein were present, while myosin was barely detectable in vesicles. Vesicles contained all phospholipid species of intact platelets and cholesterol but almost 50% of phospholipids in vesicles was dilauroylglycerophosphocholine. The phospholipid to protein ratio in vesicles was about 6.5-times higher than in intact platelets.
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PMID:Vesiculation of platelet plasma membranes. Dilauroylglycerophosphocholine-induced shedding of a platelet plasma membrane fraction enriched in acetylcholinesterase activity. 649 86

The movements of leukocytes involve extension, flow, and contraction of a margin of organelle-excluding cytoplasm. Actin is the principal structural component of this region. This paper reviews evidence that the expansion of cortical cytoplasm can result from the growth of actin polymers into an orthogonal network in which actin fibers branch perpendicularly under the influence of actin-binding protein. Flow occurs when actin filaments are disassembled and severed. The assembly and fragmentation of actin are regulated by actin-modulating proteins such as profilin, which sequesters actin monomers, acumentin, which binds to the slow-growing end of actin fibers, and gelsolin, a calcium-regulated protein that binds to the fast-growing end of actin polymers and severs actin filaments. Contraction of the actin network is caused by myosin, the assembly and activity of which are regulated by its state of phosphorylation, which is in turn controlled by phosphorylating and dephosphorylating enzymes and by calmodulin and calcium. Present information leads to the prediction that intracellular calcium gradients guide cytoplasmic movement and that the direction of actin assembly and therefore of cytoplasmic extension is toward regions of low cytoplasmic free calcium.
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PMID:The motor of leukocytes. 654 Jul 18

Stimulation of platelets by thrombin causes an increase in the amount of cytoskeleton proteins insoluble in 1% Triton X-100, i.e. myosin, actin, actin-binding protein, an alpha-actinin-like protein of Mr = 105,000, unidentified polypeptides of Mr = 150,000, 31,00, and under some conditions, 56,000. Concurrently the Mr = 20,000 light chains of myosin and a cytoplasmic Mr = 42,000 polypeptide are phosphorylated, presumably by calmodulin-Ca2+-dependent myosin light chain kinase and a phospholipid-Ca2+-dependent kinase, respectively. The adenylate cyclase stimulators prostaglandin D2 (PGD2) and forskolin increased platelet cyclic AMP and prevented the phosphorylation of these polypeptides and the increase in Triton-insoluble cytoskeleton proteins. When added to platelets after stimulation by thrombin they caused rapid complete reversal of myosin light chain and Mr = 42,000 polypeptide phosphorylation; simultaneously the association of myosin with the cytoskeleton proteins and the increase in the content of each of the Triton-insoluble cytoskeleton proteins (except the Mr = 56,000 polypeptide) was reversed. The amount of Triton-insoluble myosin was affected more readily by PGD2 or forskolin than were the other proteins. Increasing thrombin from 0.1 to 1.0 unit/ml inhibited all the responses to PGD2 and forskolin possibly due to concentration-dependent effects of thrombin that inhibit adenylate cyclase. These results suggest that cytoskeleton assembly and activation of the contractile apparatus in intact platelets are readily reversible by cyclic AMP-dependent reactions.
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PMID:Reversal of thrombin-induced myosin phosphorylation and the assembly of cytoskeletal structures in platelets by the adenylate cyclase stimulants prostaglandin D2 and forskolin. 657 35

A regulated, coordinated movement of the cytoplasm is essential for the function of phagocytes. In these cells, as in muscle cells, the power unit for movement consists of the contractile proteins, actin and myosin, which are concentrated in the region of the cell cortex. In the peripheral cytoplasm, actin fibres may be in a fluid state or they may form a gel network by association with a homodimeric, actin-binding protein. The reversible transformation of the cytoplasm from gel to sol is mediated by a regulatory protein called gelsolin, which when activated by micromolar concentrations of Ca2+, causes shortening of actin fibres, leading to disintegration of the gel network. This gel network reforms if the Ca2+ concentration falls below the threshold value for the activation of gelsolin. Ca2+, acting via gelsolin, is a second component in this system; it controls the order of events that start on the plasma membrane of the phagocyte in response to a stimulus, and are then maintained by an appropriate reaction of the contractile unit. It is to be expected that the elucidation of the molecular mechanisms that release and regulate the movement of cytoplasm in the cell will permit an understanding of factors that interfere with leukocyte function.
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PMID:How phagocytic leukocytes move. 663 36

Several proteins (eg. actin, myosin, and actin-binding protein) in the Triton-insoluble residue of thrombin-stimulated platelets are important in the formation of cytoskeletal structures. Electrophoretic analyses have shown that unidentified protein bands of 68,000, 55,000, and 48-50,000 daltons are also present in larger amounts after thrombin stimulation. Since these molecular weights correspond roughly to those of the alpha, beta, and gamma chains of fibrin, and since fibrinogen is found in platelet alpha-granules, these bands were compared to those obtained when purified fibrinogen was treated with thrombin, exposed to 1% Triton X-100-5 mM EGTA, and the resultant Triton-insoluble residue sedimented. Identification of the 68,000-, 55,000-, and 48-50,000-dalton bands as fibrinogen derivatives was confirmed by identifying them in comigration studies and in autoradiographs of Triton-insoluble residues of platelets that were electrophoretically transferred to nitrocellulose paper and treated with antifibrinogen antibody and 125I-protein A. Furthermore, if the platelet suspension was treated with thrombin in the presence of calcium ions, protein bands characteristic of the action of Factor XIII on fibrin were observed, active platelet Factor XIII apparently having been made available by lysis of platelets during preparations. Making use of the electrophoretic properties of tubulin recently described by Best et al [1981], comigration studies using hog brain tubulin indicated that tubulin is not present in significant amounts in the Triton-insoluble residue of platelets as previously suggested. The identification of these proteins as fibrinogen derivatives does not demonstrate a physiological interaction between fibrin and the platelet cytoskeleton, since fibrin is Triton-insoluble and can be pelleted even in the absence of platelet cytoskeletons.
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PMID:Identification of fibrinogen derivatives in the Triton-insoluble residue of human blood platelets. 668 14

The quantity of myosin, actin, and actin-binding protein (ABP) in platelets and platelet fractions of 5 patients with Glanzmann's thrombasthenia were compared to those of normal individuals. No significant differences were observed between the average amounts of these contractile proteins in unfractionated platelets or platelet membrane obtained after osmotic shock. However, the amount of myosin was significantly decreased in the KCl extract of thrombasthenic platelets ruptured by freezing and thawing,while its specific ATPase activity was increased.
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PMID:Distribution of myosin, actin and actin-binding protein in thrombasthenic platelets. 676 20

Proteases can complicate the characterization of proteins from cells, especially human polymorphonuclear leukocytes (PMN), which contain abundant neutral proteases. We tested the ability of agents to inhibit proteolysis, with special reference to the subunit polypeptides of the contractile proteins actin, myosin, and actin-binding protein (ABP). Phenylmethylsulfonyl fluoride (PMSF), O-phenanthroline, EGTA, EDTA, N-ethylmaleimide, alone or in combinations, failed to prevent extensive proteolysis of the PMN proteins during solubilization of cells with dodecyl sulfate. These inhibitors and also alpha-1-antitrypsin and soybean trypsin inhibitor similarly could not prevent proteolysis during homogenization of cells in cold isosomolar sucrose. Treatment of PMN with greater than or equal to mM diisopropylfluorophosphate (DFP) prior to solubilization or homogenization markedly inhibited proteolysis. PMSF and DFP were equally effective in inhibiting proteolysis in PMN extracts, suggesting that the efficacy of DFP may result from its permeation of intact cells and granules before barriers are disrupted by detergents or homogenization. Treatment of PMN with DFP under conditions inhibiting proteolysis did not affect their rate of phagocytosis. We recommend the use of DFP in future studies correlating functions and protein structure of PMN.
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PMID:Prevention of degradation of human polymorphonuclear leukocyte proteins by diisopropylfluorophosphate. 677 6


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