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)

The intracellular distributions of the cation-independent mannose 6-phosphate receptor (MPR) and a 120-kD lysosomal membrane glycoprotein (lgp120) were studied in rat hepatoma cells. Using quantitative immunogold cytochemistry we found 10% of the cell's MPR located at the cell surface. In contrast, lgp120 was not detectable at the plasma membrane. Intracellularly, MPR mainly occurred in the trans-Golgi reticulum (TGR) and endosomes. lgp120, on the other hand, was confined to endosomes and lysosomes. MPR was present in both endosomal tubules and vacuoles, whereas lgp120 was confined to the endosomal vacuoles. In cells incubated for 5-60 min with the endocytic tracer cationized ferritin, four categories of endocytic vacuoles could be discerned, i.e., vacuoles designated MPR+/lgp120-, MPR+/lgp120+, MPR-/lgp120+, and vacuoles nonimmunolabeled for MPR and lgp120. Tracer first reached MPR+/lgp120-, then MPR+/lgp120+, and finally MPR-/lgp120+ vacuoles, which are assumed to represent lysosomes. To study the kinetics of appearance of endocytic tracers in MPR-and/or lgp120-containing pools in greater detail, cells were allowed to endocytose horse-radish peroxidase (HRP) for 5-90 min. The reduction in detectability of MPR and lgp120 antigenicity on Western blots, due to treatment of cell homogenates with 3'3-diaminobenzidine, was followed in time. We found that HRP reached the entire accessible pool of MPR almost immediately after internalization of the tracer, while prolonged periods of time were required for HRP to maximally access lgp120. The combined data suggest that MPR+/lgp120+ vacuoles are endocytic vacuoles, intermediate between MPR+/lgp120-endosomes and MPR-/lgp120+ lysosomes, and represent the site where MPR is sorted from lgp120 destined for lysosomes. We propose that MPR is sorted from lgp120 by selective lateral distribution of the receptor into the tubules of this compartment, resulting in the retention of lgp120 in the vacuoles and the net transport of lgp120 to lysosomes.
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PMID:Sorting of mannose 6-phosphate receptors and lysosomal membrane proteins in endocytic vesicles. 284 7

Single stages of histiotypic formation from dissociated embryonic brain cells are described. The first stage, i.e. primary adhesion, is a phenomenon depending mainly on physicochemical features of the adhesive system. The composition of the membrane glycoprotein coat was studied during membrane regeneration and formation of cellular contacts. At the beginning single terminal sugar components and negative sialic acid residues are distributed non-homogeneously over the membrane according to the ligation of lectins. During the formation of cellular contacts this non-homogeneity progressively disappears, the thickness of the layer is reduced, however, the density of single markers increases. The highest increase of both density and layer thickness during the phase of membranes reparation occurs when the negative surface groups are labelled with cationized ferritin. The sorting out process was studied in mixed cultures as a stage of final specific recognition. It is assumed that the reaggregation of cells is a multistep process depending on maturation of the glycoprotein coat, characterized by multiple cellular adhesion and deadhesion, completed by specific recognition and fixation of recognized cells.
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PMID:The organization and differentiation of nervous cells in tissue cultures (a minireview). 294 75

Transferrin is taken up by receptor-mediated endocytosis into intracellular vesicles and tubules, and then recycles rapidly to the plasma membrane (diacytosis). We applied double-label cytochemistry to study whether the recycling structures containing transferrin fuse with the intracellular membranous structures that deliver newly synthesized membrane glycoproteins from the ER to the plasma membrane (exocytosis) or whether they remain independent. KB and Vero cells were infected with the temperature-sensitive transport mutant 0-45 of vesicular stomatitis virus (VSV). Temperature-regulated exocytosis of membrane glycoprotein "G" occurred simultaneously with diacytosis of transferrin. The exocytic "G" protein, as detected by immunoperoxidase electron microscopy, passed through the cisternal Golgi stacks and vacuolar, tubular, vesicular, and pit-like structures of the Golgi system. A transferrin-ferritin conjugate used in ultrastructural double-label experiments was detected in diacytic vesicles and tubules that accumulated in the proximal (trans-reticular) Golgi area of the cell. The ferritin-labeled vesicles/tubules were often close to and intermixed with the VSV-"G" containing membranous structures, but in most cases at early times (15-20 min) the transferrin and VSV-"G" containing vesicular structures remained distinct. At later times (30-45 min), the two labels were occasionally found in the same structures. These results indicate that rapid recycling of endocytosed materials and exocytosis of membrane glycoproteins to the cell surface usually occur in distinct vesicles, possibly along the same general morphologic exit pathway.
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PMID:Comparison of the intracellular pathways of transferrin recycling and vesicular stomatitis virus membrane glycoprotein exocytosis by ultrastructural double-label cytochemistry. 302 94

Ehrlich ascites tumor cells were strongly agglutinated by 0.4 micrograms/mL Griffonia simplicifolia I-B4 isolectin (GS I-B4), indicating the presence of nonreducing terminal alpha-D-galactopyranose (alpha-D-Galp) residues on the cell surface. Incubation of the cells with GS I-B4 labeled with either fluorescein isothiocyanate (FITC-B4) or ferritin followed by examination with the light and electron microscope revealed a random distribution of alpha-D-Galp residues over the entire cell surface. Cell-binding studies with [3H]propionate-labeled GS I-B4 demonstrated a minimum of 18.1 X 10(6) alpha-D-Galp sites per Ehrlich cell. An enriched Ehrlich cell plasma membrane preparation subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and stained with FITC-B4 revealed a number of alpha-D-galactosyl-containing glycoproteins ranging in molecular weight from 50 000 to over 200 000. The major plasma membrane glycoprotein of the Ehrlich cell (GP 130) was isolated in near homogeneous form by using nonionic detergent extraction, affinity chromatography over GS I-Sepharose 4B, and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Injection of Ehrlich cells into the mouse peritoneal cavity stimulated the appearance of low levels of alpha-D-galactosyl-containing glycoproteins in the ascites fluid ranging in molecular weight from 34 000 to 260 000. These glycoproteins differed in molecular weight when compared to the alpha-D-galactosyl-containing glycoproteins observed in either ascites fluid induced with Freund's complete adjuvant or the glycoproteins in the Ehrlich cell plasma membrane.
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PMID:Occurrence of alpha-D-galactosyl-containing glycoproteins on Ehrlich tumor cell membranes. 665 64

An experimental approach is described that enables the analysis of interactions between exogenous surface ligands and components of the cytoplasm in neutrophil leukocytes. Neutrophils treated with the nonionic detergent Lubrol PX, under controlled conditions, yield intact detergent-insoluble ghosts. Morphological analysis of neutrophil ghosts shows that they retain the original dimensions of the cell and consist almost entirely of a peripheral filamentous network, representing the submembranous cortical web, concentric to nuclear remnants. All intracellular membrane-bounded organelles, plasma membrane, and background cytoplasmic electron density are absent. Biochemical analysis of the ghosts shows that less than 10% of enzyme markers for the soluble and granule fractions remain, and that greater than 90% of total cell phospholipid is removed during detergent extraction. The major proteins remaining in the ghosts comigrate, on polyacrylamide gels in the presence of SDS, with chicken gizzard actin, myosin, filamin, and a 110-kdalton protein. Patches and caps induced on neutrophils with either fluorescein isothiocyanate-concanavalin A or ferritin-concanavalin A retain their original location and morphology on ghosts after lysis, as determined by both fluorescence and electron microscopy. In similar experiments, but using 125I-labeled lectins, 37% of total cell bound concanavalin A (Con A) and 25% succinylated Con A remain attached to the ghosts. A major 125I-labeled membrane glycoprotein (80 kdaltons) is associated with ghosts prepared from intact neutrophils iodinated in the presence of exogenous lactoperoxidase. Further 125I-labeled membrane glycoproteins (217, 170, and 147 kdaltons) become associated with ghosts prepared from iodinated cells treated before lysis with Con A, but not with succinylated Con A. These data taken together suggest that linkages exist in neutrophils between proteins exposed on the outer surface of the plasma membrane and the peripheral filamentous network independent of the presence of lipid bilayer. The implications of these findings for surface motile phenomena will be discussed.
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PMID:Transmembrane linkage between surface glycoproteins and components of the cytoplasm in neutrophil leukocytes. 719 81

We have previously described an estrogen inducible, intracellular, homodimeric membrane glycoprotein (subunit Mr 104 kDa) which is structurally related to 'chaperone' proteins (Poola, I. and Kiang J.G., J. Biol. Chem. 269 (1994) 21762-21769). In this report we describe a novel finding that the 104 kDa chaperone protein exhibits affinity for iron containing proteins such as transferrins from several species, human lactoferrin and microbial ferric binding protein (FBP). A single ferric ion in the above proteins appears to be sufficient for binding. It also binds to immobilized ferritin. However, it does not exhibit any affinity for apotransferrins, apolactoferrin, apoferritin and apoFBP. This is the first report of a chaperone protein that exhibits affinity for iron containing proteins.
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PMID:An estrogen inducible 104 kDa chaperone glycoprotein binds ferric iron containing proteins: a possible role in intracellular iron trafficking. 936 99