Functions of MAPR (Membrane-Associated Progesterone Receptor) Family Members As Heme/Steroid-Binding Proteins

ABSTRACT A brief review of the characteristics of steroid binding proteins found in the plasma and in some target organs is presented, followed by some general remarks on binding »specificity« and binding parameters. Useful techniques for measuring binding parameters at equilibrium are reported, both those which keep the equilibrium intact and those which implicate its disruption. A concept is developed according to which the determination of a specific steroid binding protein is based on the »differential dissociation« of the several steroid binding complexes present in most biological mixtures. Methods which allow determination of the kinetic parameters of the binding systems are also presented. Various representations of the binding and therefore different modes of graphic representation and calculation are discussed, including the recent »proportion graph« method.

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Serum Steroid Binding Proteins and the Bioavailability of Estradiol in Relation to Breast Diseases2

JNCI Journal of the National Cancer Institute ◽

10.1093/jnci/75.5.823 ◽

1985 ◽

Vol 75 (5) ◽

pp. 823-829 ◽

Cited By ~ 38

Author(s):

Mark S. Langley ◽

Geoffrey L. Hammond ◽

Alan Bardsley ◽

Ronald A. Sellwood ◽

David C. Anderson

Keyword(s):

Binding Proteins ◽

Steroid Binding Proteins ◽

Steroid Binding

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Application of Liquid-Liquid Partition Chromatography (LLPC) in the Preparation of Steroid Binding Proteins

Separations Using Aqueous Phase Systems ◽

10.1007/978-1-4684-5667-7_62 ◽

1989 ◽

pp. 393-399 ◽

Cited By ~ 1

Author(s):

Arnulf Heubner ◽

Michael Juchem ◽

Werner Müller ◽

Kunhard Pollow

Keyword(s):

Binding Proteins ◽

Partition Chromatography ◽

Steroid Binding Proteins ◽

Steroid Binding

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CHARACTERIZATION AND ASSAY OF THE PROGESTERONE RECEPTOR IN RAT UTERINE CYTOSOL

Journal of Endocrinology ◽

10.1677/joe.0.0760021 ◽

1978 ◽

Vol 76 (1) ◽

pp. 21-31 ◽

Cited By ~ 33

Author(s):

M. T. VU HAI ◽

E. MILGROM

Keyword(s):

Progesterone Receptor ◽

Receptor Complexes ◽

High Affinity ◽

Receptor Sites ◽

Natural Hormone ◽

Corticosteroid Binding Globulin ◽

Steroid Binding Proteins ◽

Steroid Binding ◽

High Concentrations ◽

Synthetic Progestogen

SUMMARY The synthetic progestogen R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione) binds with high affinity (Ka = 8·8 × 108 1/mol at 0 °C) to the progesterone receptor from rat uterine cytosol. At nanomolar concentrations, equilibrium is attained in less than 90 min. R5020 has a very low affinity for other specific steroid-binding proteins (corticosteroid-binding globulin and oestrogen receptors) present in relatively high concentrations in the uterine cytosol. The affinity of the receptor for the natural hormone progesterone is remarkably low (Ka= 1 × 108−1·7 × 1081/mol at 0 °C) which explains the instability of progesterone–receptor complexes. Advantage may be taken of this property to remove endogenous progesterone easily by charcoal treatment at 0 °C, a treatment which does not modify the concentration of receptors. A method based on these characteristics is described for the assay of the total number (progesterone-bound and unbound) of receptor sites in uterine cytosol. This assay may be used in various physiological situations where endogenous progesterone is present at unknown concentrations.

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