Human placental membrane receptor for IgG. Purification of the receptor and its subunit structure

Mikulska, J; Boratyński, Janusz; Niezgódka, M; Lisowski, J

doi:10.1016/0165-2478(82)90098-0

Cited by 16 publications

(7 citation statements)

References 21 publications

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“…Attempts to identify the placental IgG receptor have led to the characterization of several IgG binding proteins [8][9][10][11], including annexin II [12] and placental alkaline phos-phatase (PLAP) [13][14][15]. Although our recent data do not support a role of PLAP in IgG internalization in BeWo or PLAP-transfected MDCK cells [16], a possible function of annexin II in IgG endocytosis in syncytiotrophoblasts has not been analyzed so far [17].…”

Section: Introductionmentioning

confidence: 80%

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

et al. 1999

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In primates, prenatal transfer of IgG from mother to offspring occurs predominantly across the placenta. Although a number of Fcgamma-receptors and IgG binding proteins have been detected in human placental tissue, an involvement of any of these receptors in IgG transport across the syncytiotrophoblast remains to be demonstrated. Therefore, we investigated the mechanism of IgG transcytosis in trophoblast-derived BeWo cells. BeWo cells were not only found to express the MHC class I-related IgG Fc receptor, human FcRn, but also specifically bound fluorescein isothiocyanate (FITC)-labeled human IgG (FITC-hIgG) at the apical surface at mildly acidic pH. The cells preferentially transcytosed FITC-hIgG from the apical to the basolateral side when compared to the fluid-phase marker FITC-dextran and to FITC-hIgG transcytosis in the opposite direction. However, endocytosis of FITC-hIgG at the apical plasma membrane at physiological pH required the continuous presence of FITC-hIgG at concentrations similar to those present in the maternal circulation. These results suggest a mechanism by which IgG is internalized by BeWo cells via fluid-phase endocytosis. Tight binding of IgG to hFcRn may then occur in acidic endosomes, followed by selective sorting into the transcytotic pathway. Thus, the main function of this receptor is to prevent entry of IgG into the degradative pathway in lysosomes.

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Section: Introductionmentioning

confidence: 80%

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

et al. 1999

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“…The placental Fc receptor, suggested to be involved in the transport of IgG to the foetus, was purified using the method described by Mikulska ct al., slightly modified [12]. SDS/ PAGE of the purified receptor revealed, under reducing conditions, the three bands at 64, 54 and 28 kDa reported by the between the placental receptor and PLAP, the purified Fc receptor preparation was tested in Western blotting using polyclonal anti-PLAP as first antibody.…”

Section: Resultsmentioning

confidence: 99%

“…The placental Fc receptor was purified according to Mikulska with slight modifications [12]. Briefly, placental plasma membranes were extracted with phenol and exhaustively dialyzed against Tris/NaCl.…”

Section: Purification Of the Placental Fc Receptormentioning

confidence: 99%

Placental alkaline phosphatase has a binding site for the human immunoglobulin‐G Fc portion

Makiya

Stigbrand

1992

European Journal of Biochemistry

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Affinity chromatography of human plasma on placental-alkaline-phosphatase-Sepharose columns (placental alkaline phosphatase, PLAP) yielded consistently a pure protein which was identified as IgG on the basis of electrophoretical and immunological comparisons with authentic human IgG. SDS/PAGE of the protein revealed, under reducing conditions, two polypeptides of 55 kDa and 25 kDa. The N-terminal amino acid sequence (12 residues) of the 55-kDa subunit presented high similarity (83 -100O/0) with known sequences of immunoglobulin gamma chains. The IgG binds by its Fc portion to a fully exposed domain in the plasma-membrane-anchored PLAP.Scatchard analysis of the interaction gave a dissociation constant of 3.68 pM, a value close to those found for haematopoietic cells and syncytiotrophoblast Fc receptors. The latter was affinity purified from human placenta as the major IgG-binding component and presented cross-immunoreactivity with anti-PLAP antibodies, indicating that PLAP and the putative placental Fc receptor could be identical molecules.The physiological function of alkaline phosphatases is not yet clear. Except for the bone isoform, which seems to be related to bone mineralization [l], the panorama concerning the role of the remaining isozymes and isoforms is still a matter of intense investigation. The search for physiological substrates has given no conclusive results and the fact that these enzymes have their maximal catalytic activity at pH values far from the physiological range, brings about the necessity of reconsidering their role in the organism not solely as monocster phosphohydrolases hut also as proteins with structural propcrties [2]. Several cellular processes have been postulated to be associated with alkaline phosphatases. Among the putative functions for these isozymes, several might involve interactions with other proteins, i. Willebrand factor, macrophage receptor MAC-I and leucocyte adhesion receptor, suggesting that PLAP had the capability to specifically interact with other proteins as well.In the search for proteins binding to PLAP we observed clear interaction betwecn the enzyme and a normal serumCorrespondence to

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“…The identity of the receptors that carry IgG across the human placenta is not known. Several IgG-binding proteins have been isolated from placenta (2,3). FcyRII has been detected in placental endothelium (4)(5)(6)(7) and Fc3~RIII in syncytiotrophoblast (6,7).…”

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confidence: 99%

A major histocompatibility complex class I-like Fc receptor cloned from human placenta: possible role in transfer of immunoglobulin G from mother to fetus.

Story

Mikulska

Simister

1994

The Journal of Experimental Medicine

322

237

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SummaryThe acquisition of maternal antibodies is critical for immunologic defense of the newborn. In humans, maternal IgG is actively transported across the placenta. The receptor responsible for this transport has not been identified definitively. We report the isolation from a placental cDNA library of clones encoding the oe-chain of an immunoglobulin G (IgG)-Fc receptor (hFcRn) that resembles a class I major histocompatibility complex antigen. The DNA and predicted amino acid sequences are very similar to those of the neonatal rat and mouse intestinal Fc receptors, rFcRn and mFcP, n. These receptors mediate transport of maternal IgG from milk to the bloodstream of the suckling rat or mouse. Like rat and mouse FcRn, hFcR_n binds IgG preferentially at low pH, which may imply that IgG binds hFcRn in an acidic intracellular compartment during transport across the placenta.

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Human placental membrane receptor for IgG. Purification of the receptor and its subunit structure

Cited by 16 publications

References 21 publications

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

Placental alkaline phosphatase has a binding site for the human immunoglobulin‐G Fc portion

A major histocompatibility complex class I-like Fc receptor cloned from human placenta: possible role in transfer of immunoglobulin G from mother to fetus.

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