Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human erythrocyte membrane proteins solubilized with the non-ionic detergent Berol EMU-043 have been characterized by crossed immunoelectrophoresis with rabbit antibodies raised against the membrane material. Three out of sixteen membrane-specific immunoprecipitates disappeared when the antisera were first absorbed with intact erythrocytes. This finding indicates that three antigens are exposed on the outside of the erythrocyte membrane. One of these antigens showed acetylcholinesterase activity, and another was the major glycoprotein (glycophorin) as shown by crossed-line immunoelectrophoresis. No antigenic determinants of the latter protein were detected within the membrane or on its inner surface. In crossed immunoelectrophoresis with antisera after absorption with washed, non-sealed membranes only one precipitate remained. This precipitate corresponded to albumin. Accordingly, several proteins seem to have antigenic determinants exposed on the inside of the membrane.
 ...
PMID:Immunoabsorption of membrane-specific antibodies for determination of exposed and hidden proteins in human erythrocyte membranes. 4 98

Human erythrocytes incubated without glucose at 37 degrees C (in vitro aging) release spectrin-free vesicles after 12 or more hours. The release of vesicles is dependent upon ATP depletion. If the endogenous level of ATP is maintained, vesicle release is completely inhibited up to 54 h. Vesicle release is independent of hemolysis because in vitro aged cells and cells that maintain their ATP levels lose identical amounts of hemoglobin up to 45 h. 93 percent of all membrane particles released constitute a uniform population of spheres with a diameter of 185 +/- 23nm. These vesicles are of slightly varying densities due to varying contents of hemoglobin. Vesicles contain half the amount of membrane protein that is found in intact membranes when referred to the content of phospholipids phosphorus. This is primarily due to the absence of spectrin. However, their content of protein component III, glycophorin, and cholesterol remains the same as in intact membranes. Thus, the major integral membrane proteins are present in vesicles in similar quantities were surface area as in cells except for the enzyme acetylcholinesterase that is enriched up to twofold. The phospholipids composition of these vesicles is representative of the intact membrane except that the amount of phosphatidic acid is 10-fold higher and the amount of phosphatidylethanolamine is slightly lower than in erythrocytes. These results suggest a selective release of membrane domains that lack peripheral membrane proteins and are enriched in acetylcholinesterase. This release of spectrin-free vesicles from cells aged in vitro could represent an acceleration of the physiological aging process.
 ...
PMID:Release of spectrin-free vesicles from human erythrocytes during ATP depletion. I. Characterization of spectrin-free vesicles. 87 88

The protein and phospholipid composition of microvesicles released from normal human erythrocytes after ATP depletion, on aging or by treatment with merocyanine 540, dimyristoyl phosphatidylcholine or Ca2+/ionophore A23187 has been compared with the composition of the original cell membrane. It has been shown that these microvesicles are depleted of band 3, glycophorin and phosphatidylinositol 4,5-bisphosphate relative to phospholipid by 40% or more. These data are interpreted to mean that less than half of these membrane components are free to diffuse laterally in the lipid bilayer. Acetylcholinesterase was found to be enriched 2-3-fold in microvesicles, possibly because the removal of non-diffusing proteins from the vesiculating region of the lipid bilayer allows more space for freely diffusing proteins like acetylcholinesterase to enter the microvesicle membrane.
 ...
PMID:Restricted diffusion of integral membrane proteins and polyphosphoinositides leads to their depletion in microvesicles released from human erythrocytes. 217 10

A generally applicable approach to the preparative isolation of amphiphilic membrane proteins that follow the Triton X-114 phase during a temperature-dependent phase separation is described. The phase separations were performed direct on whole blood and a 650-fold purification of human erythrocyte membrane acetylcholinesterase (AchE) was obtained. Thus, 0.2 mg enzyme was isolated per 1 liter of blood, with a specific activity of 13 IU/mg, the major contaminants being glycophorin and hemoglobin. The protein material was isolated from the detergent phase by Cu2+ chelate chromatography. This material was used to raise monoclonal anti-AchE antibodies which, when applied to immunosorbent chromatography of washed Triton X-100-lysed erythrocytes in one step, allowed a 246,000-fold purification of AchE with a yield of 88% and a specific activity of 3800 IU/mg.
 ...
PMID:Isolation of human erythrocyte acetylcholinesterase using phase separation with Triton X-114 and monoclonal immunosorbent chromatography. 391 71

A population of vesicles 150 +/- 30 nm in diameter was isolated from banked human blood and the perturbation of their membrane studied. SDS polyacrylamide gel electrophoresis revealed the complete loss of spectrins from the vesicle membrane which was also depleted of various intrinsic proteins. In particular, severe reduction of protein 3 and glycophorin is consistent with the over 80% decline of intramembrane particles in either fracture face of the vesicle membrane. The stimulation of vesicle acetylcholinesterase is considered indicative of an initial disintegration associated with the segregation and rearrangement of membrane constituents. The findings are discussed with regard to the subcellular mechanisms of erythrocyte vesiculation.
 ...
PMID:Erythrocyte vesiculation. 2. Membrane molecular transformation. 617 May 53

Membrane vesicles were prepared by incubation of human erythrocytes with dimyristoylphosphatidylcholine [3] and isolated by isopycnic centrifugation on Dextran density gradients. Protein analyses were carried out with crossed immunoelectrophoresis and dodecylsulfate polyacrylamide gel electrophoresis. The right-side-out-oriented membrane vesicles contained membrane and cytoplasmic proteins of the erythrocyte but lacked cytoskeletal components. Comparison of proteins in vesicles and erythrocyte membranes showed that acetylcholinesterase was enriched two to six times in the vesicles relative to both membrane-spanning proteins, band 3, and glycophorin. Two further, hitherto unidentified, sialic acid-containing membrane antigens were found in the vesicles. Both faced the outside of the membranes and were enriched two to seven times. Ankyrin was not present in the membrane vesicles and spectrin could not be detected by dodecylsulfate polyacrylamide gel electrophoresis. We suggest that the redistribution of proteins in the vesicles reflects differences in their interactions with other membrane components and their relative mobility within the erythrocyte membrane.
 ...
PMID:Quantitative composition and characterization of the proteins in membrane vesicles released from erythrocytes by dimyristoylphosphatidylcholine. A membrane system without cytoskeleton. 618 80

Two sublines of the human leukemia cell line K562 including the original cell line and three clones have been investigated for their erythroid features. All of them produce embryonic and fetal hemoglobins, glycophorin A, spectrin and true acetylcholinesterase, but to a varying extent among the cell lines. The Hb and glycophorin contents were correlated in the different K562 cell lines, whereas acetylcholinesterase was independently expressed from these two other erythroid markers. Hb accumulation is enhanced by exposure of the cells to 100 microM hemin without a significant modification of the expression of the other erythroid markers. Butyrate greatly increased the activity of acetylcholinesterase, slightly enhanced the production of hemoglobin, but did not modify the expression of glycophorin and spectrin. 12-O-tetradecanoyl-phorbol-13-acetate (TPA) induced an almost complete disappearance of glycophorin, reduced the synthesis of Hb by K562 cells and also abolished the action of hemin on Hb accumulation. Therefore, all the different K562 cell lines exhibit clear erythroid features including acetylcholinesterase. Butyrate or hemin did not induce terminal differentiation of K562 cells, whereas TPA significantly diminished the erythroid phenotype.
 ...
PMID:Erythroid properties of K562 cells. Effect of hemin, butyrate and TPA induction. 657 18

Incubation of human erythrocytes with suspensions of sonicated dimyristoyl phosphatidylcholine resulted in dramatic morphological changes of the cells and release of membrane vesicles. The shedding of membrane vesicles was not preceded by ATP depletion and only occurred at temperatures of incubation that were above the phase transition temperature of dimyristoyl phosphatidylcholine. Membrane vesicles were separated from intact erythrocytes and exogenous dimyristoyl phosphatidylcholine by a series of centrifugation steps. The lipid composition of the membrane vesicles was similar to that of the native erythrocyte, and the predominant membrane proteins were band 3, glycophorin and acetylcholinesterase. Spectrin was not detected. Freeze-fracture electron microscopy showed vesicles (150 nm in diameter) with protein particles embedded in the lipid bilayer.
 ...
PMID:Effect of dimyristoyl phosphatidylcholine on intact erythrocytes. Release of spectrin-free vesicles without ATP depletion. 721 19

An increase in the intracellular concentration of Ca2+ in human erythrocytes results in the formation of gamma-glutamyl-epsilon-lysine cross-linked membrane protein polymers. Following solubilization of the membranes with SDS, these polymers can be isolated on a Lubrol-containing sucrose gradient. Immunoelectrophoresis of the polymeric material with a polyspecific rabbit antibody against human ghosts gave rise to a single, but heterogeneous, precipitate. The polymer was amphiphilic and, on addition to Triton-solubilized erythrocyte membrane proteins, it coprecipitated with spectrin. When the antihost antibody was absorbed with the polymer prior to cross immunoelectrophoresis of normal erythrocyte membrane proteins, the precipitates of glycophorin, acetylcholinesterase, and hemoglobin were normal, whereas the antibody titers against band 3 protein, spectrin, and ankyrin became reduced. Furthermore, a rabbit antibody raised against the isolated human polymer reacted selectively with the same three membrane proteins. No reactions occurred with lysate proteins.
 ...
PMID:An immunochemical approach for the analysis of membrane protein alterations in Ca2+-loaded human erythrocytes. 731 Aug 99