Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Release of the lysosomal enzyme beta-glucuronidase from human neutrophils was induced by IgG or its Fc fragment, aggregated by immune precipitation or by coating on latex particles. Such release was inhibited when the cells were preincubated with free IgG or Fc fragments; F(ab')2 fragments were ineffective in both inducing and inhibiting beta-glucuronidase release. Neutrophils incubated with IgG or Fc fragments, when challenged with anti-IgG antibody, released lysosomal enzymes without the release of the cytoplasmic marker lactic dehydrogenase; These studies indicate that human neutrophils have surface receptors for the Fc portion of IgG. Neutrophils treated with IgG or its Fc fragment and subsequently with fluorescein- or ferritin-labeled anti-IgG showed binding of Fc or IgG to the cell membrane. Under suitable conditions, polar capping of labeled antibody was seen by fluorescence or electron microscopy. These studies suggest that the immunoglobulin receptors on neutrophils are redistributed when they are cross-linked with antibody. Fluidity of the membrane receptors appeared to be time and temperature dependent. Compounds such as 2-deoxyglucose, colchicine, and cyclic AMP, which inhibit the release of lysosomal enzymes, also inhibited the redistribution of the surface receptors. Cytochalasin B, an agent which increases the release, was found to increase the receptor redistribution; The relationship between the release of lysosomal enzymes and receptor mobility is discussed;
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PMID:Redistribution of immunoglobulin receptors on human neutrophils and its relationship to the release of lysosomal enzymes;. 18 51

The ultrastructure of the secondary cell-mediated lympholysis (CML) reaction and the effects on interacting lymphocytes of colchicine, cytochalasin B, and effector cell-specific antisera were examined using transmission and scanning electron microscopy. Surface labelling of cytotoxic secondary effector cells with cationized ferritin allowed them to be distinguished from unlabelled target lymphocytes. Effector--target interactions were characterized by intercellular junctions involving extensive areas of membrane apposition and interdigitation and extension of pseudopod-like processes by the effector cell. The abolition of such interactions when effector populations were pretreated with anti-Ly2 sera plus complement demonstrated target cell destruction in secondary CML to be dependent on the activity of restimulated cytotoxic T lymphocytes. Cytochalasin B and colchicine dramatically decreased the numbers of specific effector--target cell interactions observed. Although the data presented do not allow the possible activity of soluble lytic factors associated with the effector cell surface to be ruled out, they suggest that target cell lysis in the secondary CML system examined results from immune-specific binding of alloantigen-sensitized effectors to targets and osmotic effects which follow localized disruption of the target cell membrane.
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PMID:Ultrastructure of effector--target cell interaction in secondary cell-mediated lympholysis. 63 73

Several lines of studies were undertaken to clarify the identity of the glucose transporter of human erythrocytes. Peptide maps of zone 4.5 which is the main component of the purified transporter fraction, were different from those of band 3. Cytochalasin B bound to the purified transporter fraction but not to band 3. Antibody raised against the purified transporter fraction cross-reacted with zone 4.5 and moderately with band 7, but not with other erythrocyte membrane proteins. These results indicate that zone 4.5 is the transporter (or a part of the transporter) and is not a fragment of band 3. With ferritin antibody electron microscopy and freeze-fracture electron microscopy, the glucose transporter were found to evenly distributed in reconstituted liposomes. Further morphological analysis coupled with transport assays showed the distribution of the transporters was random and was satisfactorily fitted to Poisson distribution, indicating reversible association of the transporters does not occur in liposomes and is not necessary for transport activity. This communication summarises our recent studies on identification and properties of the glucose transporter of human erythrocytes. A full account of the studies is published elsewhere (22, 23).
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PMID:Identification and properties of the glucose transporter of human erythrocytes. 689 54

The target cells for gene therapy of cystic fibrosis lung disease are the well differentiated cells that line airway lumens. Employing cultures of airway epithelial cells that grow like "islands" and exhibit a continuum of cellular differentiation, we studied the mechanisms that render well differentiated cells more difficult to transfect with cationic liposomes than poorly differentiated cells. The poorly differentiated cells at the edge of the islands were transfectable with liposome-DNA complexes (pCMVbeta:LipofectACE = 1:5 (w/w)), whereas the more differentiated cells in the center of the islands were not. Evaluation of the steps leading to lipid-mediated transfection revealed that edge cells bound more liposome-DNA complexes, in part due to a more negative surface charge (as measured by cationized ferritin binding), and that edge cells internalized more liposome-DNA complexes than central cells. Edge cells exhibited receptor-mediated endocytosis of LDL, pinocytosis of 10-nm microspheres, and phagocytosis of 2-microm microspheres, whereas central cells were only capable of receptor-mediated endocytosis. Cytochalasin B, which inhibited pinocytosis by 65% and phagocytosis by 93%, decreased edge cell liposome-DNA complex entry by 50%. Potassium depletion, which decreased phagocytosis by >90% but had no effect on pinocytosis, inhibited edge cell liposome-DNA complex entry by 71%. These results indicate that liposome-DNA complexes enter edge cells via phagocytosis and that this pathway is not detectable in central cells. In conclusion, both reduced negative surface charge and absence of phagocytosis internalization pathways in relatively differentiated cells may explain differentiation-dependent decrements in cationic liposome-mediated gene transfer in airway epithelia.
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PMID:Loss of binding and entry of liposome-DNA complexes decreases transfection efficiency in differentiated airway epithelial cells. 899 11