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Titolo:
Ligand binding characteristics of a glycosylphosphatidyl inositol membrane-anchored HeLa cell folate receptor epitope-related to human milk folate binding protein
Autore:
Holm, J; Hansen, SI; Hoier-Madsen, M; Korsbaek, L; Beckmann, H; Josefsen, K;
Indirizzi:
Herning Hosp, Dept Clin Chem, DK-7400 Herning, Denmark Herning Hosp Herning Denmark DK-7400 Clin Chem, DK-7400 Herning, Denmark Cent Hosp Hillerod, Dept Clin Chem, DK-3400 Hillerod, Denmark Cent Hosp Hillerod Hillerod Denmark DK-3400 m, DK-3400 Hillerod, Denmark Statens Serum Inst, Lab Autoimmune Serol, DK-2300 Copenhagen, Denmark Statens Serum Inst Copenhagen Denmark DK-2300 K-2300 Copenhagen, Denmark Municipal Hosp, Bartholin Inst, DK-1399 Copenhagen, Denmark Municipal Hosp Copenhagen Denmark DK-1399 t, DK-1399 Copenhagen, Denmark
Titolo Testata:
BIOSCIENCE REPORTS
fascicolo: 2, volume: 20, anno: 2000,
pagine: 109 - 118
SICI:
0144-8463(200004)20:2<109:LBCOAG>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMINO-ACID-SEQUENCE; COWS MILK; RADIOLIGAND BINDING; HYDROPHOBIC DOMAIN; CHOROID-PLEXUS; AFFINITY; IMMUNOREACTIVITY;
Keywords:
ligand binding; glycosylphosphatidyl inositol anchor; epitope-relatedness to human milk folate binding protein;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
18
Recensione:
Indirizzi per estratti:
Indirizzo: Holm, J Herning Hosp, Dept Clin Chem, DK-7400 Herning, Denmark Herning Hosp Herning Denmark DK-7400 m, DK-7400 Herning, Denmark
Citazione:
J. Holm et al., "Ligand binding characteristics of a glycosylphosphatidyl inositol membrane-anchored HeLa cell folate receptor epitope-related to human milk folate binding protein", BIOSCI REP, 20(2), 2000, pp. 109-118

Abstract

The folate receptor (FR) in HeLa cells was characterized as to ligand binding mechanism, antigenic properties and membrane anchor in order to obtain information to be used for the design of biological agents targeting FR in malignant tumors. The receptor displayed the following binding characteristics in equilibrium dialysis experiments (37 degrees C, pH 7.4) with [H-3] folate: a high-affinity type of binding that exhibited positive cooperativity with a Hill coefficient > 1.0 and an upward convex Scatchard plot, a slowradioligand dissociation at pH 7.4 becoming rapid at pH 3.5 and inhibitionin the presence of other folates. The molecular size of the receptor was 100 kDa on gel filtration with Triton X-100, or similar to that of high molecular weight human milk folate binding protein (FBP). The latter protein represents a 25 kDa molecule which equipped with a hydrophobic glycosylphosphatidyl inositol (GPI) membrane anchor susceptible to cleavage by phosphatidylinositol specific phospholipase C (PI-PLC) forms micelles of 100 kDa sizewith Triton X-100. The HeLa cell FR immunoreacted with antibodies against purified human milk FBP in ELISA, and in a fluorescence activated cell sorting system, where HeLa cells exposed to increasing concentrations of antibody showed a dose-dependent response. Exposure to PI-PLC decreased the fraction of immunolabeled cells indicating a linkage of FR to cell membranes by a GPI anchor. HeLa cells incubated with radiofolate showed a continuous uptake with time, however, with a complete suppression of uptake in the presence of an excess of cold folate. Prewash of cells at acidic pH to remove endogenous folate increased the uptake. Binding and uptake of [H-3] folate wasincreased in cells grown in a folate-deprived medium. The HeLa FR seems tobe epitope related to human milk FBP.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 13:39:17