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Neuschäfer-Rube, Frank ; Püschel, Gerhard ; Jungermann, Kurt
Characterization of prostaglandin-F₂α-binding sites on rat hepatocyte plasma membranes
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Kurzfassung auf Englisch
Prostaglandin (PG)F₂α has previously been shown to increase glucose output from perfused livers and isolated hepatocytes, where it stimulated glycogen phosphorylase via an inositol-trisphosphatedependent signal pathway. In this study, PGF₂α binding sites on hepatocyte plasma membranes, that might represent the putative receptor, were characterized.Binding studies could not be performed with intact hepatocytes, because PGF₂α accumulated within the cells even at 4°C. The intracellular accumulation was an order of magnitude higher than binding to plasma membranes.
Purified hepatocyte plasma membranes had a high-affinity/low-capacity and a low-affinity/highcapacity binding'site for PGF₂α. The respective binding constants for the high-affinity site were Kd = 3 nM and Bmax = 6 fmol/mg membrane protein, and for the low-affinity site Kd = 426 nM and Bmax = 245 fmol/mg membrane protein.
Specific PGF₂α binding to the low-affinity site, but not to the high-affinity site, could be enhanced most potently by GTP[γS] followed by GDP[ϐS] and GTP, but not by ATP[γS] or GMP.
PGF₂α competed most potently with [³H]PGF₂α for specific binding to hepatocyte plasma membranes, followed by PGD₂ and PGE₂.
Since the low-affinity PGF₂α-binding site had a Kd in the concentration range in which PG had previously been shown to be half-maximally active, and since this binding site showed a sensitivity to GTP, it is concluded that it might represent the receptor involved in the PGF₂α signal chain in hepatocytes. A biological function of the high-affinity site is currently not known.
| Institut: | Institut für Ernährungswissenschaft | |
| DDC-Sachgruppe: | Biowissenschaften, Biologie | |
| Dokumentart: | c Postprint | |
| Schriftenreihe: | Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe, ISSN 1866-8372 | |
| Band Nummer: | paper 113 | |
| Quelle: | European Journal of Biochemistry 211 (1993), 1-2, p. 163-169, DOI 10.1111/j.1432-1033.1993.tb19883.x, ISSN 0014-2956 | |
| Sprache: | Englisch | |
| Erstellungsjahr: | 1993 | |
| Publikationsdatum: | 04.08.2010 | |
| Bemerkung: |
first published in: FEBS Journal - 211 (1993), 1-2, p. 163-169 ISSN: 0014-2956 doi: 10.1111/j.1432-1033.1993.tb19883.x |
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