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Specificity studies of particulate binding sites for steroid hormones in subcellular fractions of the porcine corpus luteum
- Source :
- Journal of Endocrinology. 136:371-380
- Publication Year :
- 1993
- Publisher :
- Bioscientifica, 1993.
-
Abstract
- We have studied the binding of a number of radiolabelled steroids and lipophilic substances to porcine corpus luteum (CL) particulate fractions. Following preincubation of CL homogenates with radiolabelled progesterone or pregnenolone prior to fractionation on continuous sucrose density gradients, a broad peak of binding was observed associated with a particulate fraction of buoyant density 1·05–1·10 g/cm3. Progesterone content also peaked at a similar buoyant density (1·06–1·12 g/cm3). Pretreatment of luteal homogenates with digitonin perturbed the buoyant density of the progesterone-binding particulate fraction to 1·10–1·14 g/cm3 and sharpened the binding peak. Progesterone content was also perturbed to a similar extent by digitonin pretreatment, without release of the steroid. Oestrogens were also sequestered by this fraction, but steroid precursors (cholesterol, cholesterol ester), corticosteroids (cortisol, corticosterone), sterol conjugates (oestrone sulphate, pregnanediol glucuronide) and other lipophilic substances (arachidonic acid, phospholipid, prostaglandins E1, E2 and F2α) were not bound. Androgens were bound weakly by fractions from control gradients but, in the presence of digitonin, significant binding could be demonstrated. Radiolabelled steroids were shown to interact directly with luteal membrane fractions, rather than interacting first with cytosolic steroid receptors which then bound to membranes. Furthermore, [3H]progesterone was not bound by porcine granulosa cell particulate fractions. These observations suggest that this fraction may be involved in sequestration or packaging of progesterone for secretion by the luteal cell. Journal of Endocrinology (1993) 136, 371–380
- Subjects :
- medicine.medical_specialty
Swine
Endocrinology, Diabetes and Metabolism
Granulosa cell
medicine.medical_treatment
Digitonin
Biology
Luteal phase
Steroid
chemistry.chemical_compound
Cytosol
Endocrinology
Corpus Luteum
Internal medicine
Centrifugation, Density Gradient
medicine
Animals
Gonadal Steroid Hormones
Progesterone
Binding Sites
Granulosa Cells
Cell Membrane
Sterol
Steroid hormone
medicine.anatomical_structure
chemistry
Pregnenolone
Female
Corpus luteum
Subcellular Fractions
medicine.drug
Subjects
Details
- ISSN :
- 14796805 and 00220795
- Volume :
- 136
- Database :
- OpenAIRE
- Journal :
- Journal of Endocrinology
- Accession number :
- edsair.doi.dedup.....c90ffe2cb6b8276e2dc1db9736045ea0