Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytosol prepared from epididymides of castrated adult rabbits contains an estrogen-specific binding component that sediments in the 4--5S region on 0.01 M KCl sucrose gradients. The estrogen-specific binding component is not detectable on sucrose gradients unless the cytosol-[3H]estradiol mixture is first extracted with charcoal to remove uncomplexed and rapidly exchangeable ligand from the sample. The macromolecular bound [3H]estradiol that remains after charcoal extraction dissociates from the receptor with a dissociation half-time of greater than 24 h and is of high affinity (Kd = 6.5 +/- 0.9 X 10(-9) M). The estrogen receptor in the adult rabbit epididymis can also be demonstrated when charcoal-extracted samples are chromatographed on Sephadex G-200. Using this system, the major estrogen-specific binder has an apparent molecular weight of less than 200,000. In contrast, the epididymal estrogen receptor in sexually immature rabbits sediments as an 8S species on low salt gradients and has an apparent molecular weight of 200,000 or greater when assessed by chromatography on Sephadex G-200. The estrogen receptor in both age groups is distributed along the length of the epididymal duct. The highest concentration of the cytoplasmic receptor in both mature and immature rabbits is in the cauda epididymidis. The age-dependent changes in the amount of the receptor suggest that it may be involved in maturational changes in the epididymis. The alterations in the physicochemical properties may reflect physiological changes in the epididymis or in the endocrine status of the animal.
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PMID:The presence of a cytoplasmic estrogen receptor in sexually mature rabbit epididymides: comparison with the estrogen receptor in immature rabbit epididymal cytosol. 48 1

The nuclear estrogen receptor was characterised in isolated rat adipocytes. The binding reaction with [3H]estradiol was performed with intact isolated rat adipocytes and the radioactivity associated with the nucleus was subsequently determined after cell lysis. The nuclear uptake of [3H]estrogen in rat adipocytes was temperature dependent and steroid specific. The steady-state binding was achieved after 30 min at 37 degrees C and was constant for several hours. Estradiol was found to bind to a homogeneous class of nuclear receptors in epididymal adipocytes with an apparent Kd of 3.1 +/- 0.76 nM and a Bmax of 7.98 +/- 1.11 fmol/10(6) cells corresponding to about 4800 receptors per nucleus. The estradiol binding exhibited regional variations in isolated adipocytes. In lean rats the highest receptor number was found in epididymal adipocytes, whereas there was a significantly lower number of nuclear binding sites in perirenal and subcutaneous adipocytes (P less than 0.05), unlike in older and more obese rats where the nuclear estradiol binding was greatest in adipocytes from the perirenal fat depot. Incubations with isoproterenol (10 microM) and dibutyryl-cAMP (2.5 mM) both reduced estradiol binding by 56% (P less than 0.005), while insulin (1 nM) enhanced the estradiol binding by 37% (P less than 0.01). In conclusion, a specific and high affinity nuclear estradiol receptor was demonstrated in rat adipocytes and regional differences in nuclear estradiol binding were detected. Furthermore, it was demonstrated that nuclear estradiol binding could be modulated by other agents known to affect adipocyte metabolism.
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PMID:Nuclear estradiol binding in rat adipocytes. Regional variations and regulatory influences of hormones. 164 50

The nucleomyofibrillar fraction of mature rabbit epididymides contains a salt-extractable and leupeptin-sensitive protease that alters the sedimentation coefficient of cytosolic steroid receptors. We refer to this modification as receptor conversion. The substrate used in these studies was cytosolic estrogen receptor obtained from frozen rabbit uteri. The unactivated form of the receptor exists as an oligomer under hypotonic (0.01 M KCl) conditions (S20,w congruent to 9.6, Stokes radius (Rs) congruent to 7.4 nm, Mr congruent to 320,000) and dissociates under hypertonic (0.4 M KCl) conditions to yield the steroid-binding monomer (S20,w congruent to 4.7, Rs congruent to 5.1 nm, Mr congruent to 104,000). According to analysis under hypotonic conditions, the epididymal protease disrupts the oligomeric architecture of the receptor and reduces the size of the steroid-binding monomer (S20,w congruent to 3.2, Rs congruent to 3.0 nm, Mr congruent to 42,000). The epididymal protease had no detectable effect on the structure of the proteins used as standards for the ultracentrifugal or gel filtration analyses. Although inhibited by leupeptin, the epididymal enzyme is not a typical thiol protease since it was unaffected by thiol-blocking agents (iodoacetamide and N-ethylmaleimide), and was partially inhibited by thiol-reducing agents (monothioglycerol and dithiothreitol). Calcium and magnesium ions alone, or in combination with ATP, had no effect on the activity of the protease. However, both cations selectively suppressed recovery of the oligomeric receptor form. These results, in conjunction with those from previous studies, serve to distinguish the epididymal protease from receptor-active proteases described in extracts of other animal tissues. Molybdate, at a concentration of 50 mM, blocked receptor conversion. The ability of the receptor to be stabilized by molybdate was lost following conversion. Finally, the epididymal protease appears to remove a portion of the estrogen receptor that is necessary for nucleotide-binding.
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PMID:Further characterization of a steroid receptor-active protease from the mature rabbit epididymis. 353 65

We have previously shown that the cytosolic estrogen receptor in adult rabbit epididymides sediments as an congruent to 3 S species on sucrose gradients containing 0.01 M KCl while that from immature rabbit epididymides sediments at congruent to 9 S. This age-dependent decrease in sedimentation coefficient is attributable to the appearance of a leupeptin-sensitive protease as the animals mature. We now show that if adult epididymides are homogenized in buffer containing leupeptin, the 9 S receptor can be demonstrated, indicating inhibition of receptor degradation. In vitro nuclear uptake studies conducted in the absence of leupeptin indicated that the proteolyzed receptor was not an efficient nuclear binder. When leupeptin was present, nuclear uptake increased 6-fold and it was accompanied by depletion of receptor from the cytosol. Binding of the receptor to nuclei was specific since it could be inhibited by unlabeled estrogens but not by unlabeled 5 alpha-dihydrotestosterone or progesterone. In vitro mixing experiments indicated that the proteolytic activity was associated with the crude nuclear fraction since, in the absence of leupeptin, they had reduced ability to bind estrogen receptor present in immature epididymal cytosol. Specific in vivo binding of [3H]estradiol by adult and immature rabbit epididymides could be demonstrated. The time course of in vivo binding of [3H]estradiol by adult rabbit epididymal nuclei indicated maximum binding (70 fmol/g tissue) at 30 min following injection. By 60 min, the amount of binding had decreased to about 25 fmol. The accessory sex organs, which do not contain the protease, also exhibited maximum binding (150 fmol/g tissue) at 30 min. However, at the 60 min period binding was still about 140 fmol. Processing the tissues in buffers containing leupeptin had no effect on the results obtained. These results are interpreted to indicate that the presence of the protease decreases nuclear binding of the estrogen receptor and shortens nuclear occupancy. This combination of factors may be responsible for the decrease in estrogen action in the adult rabbit epididymis.
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PMID:A protease acting on the estrogen receptor may modify its action in the adult rabbit epididymis. 353 67

Epididymides from sexually mature rabbits contain a factor that induces a discrete reduction in the sedimentation coefficient of cytosolic estrogen receptors from various tissues (rabbit epididymis and accessory sex organs; rabbit, rat and mouse uterus) and of cytosolic progesterone receptors from the rabbit uterus. The factor is not species-specific since a similar activity was detected in extracts of mature rat epididymides. Although present in cytosol, the factor is obtained in much higher yield in hypertonic extracts of the nucleomyofibrillar fraction of mature rabbit epididymal tissue. Using rabbit uterine estrogen receptor as substrate, we have determined the following details about the rabbit epididymal factor: (1) it is tissue-specific (undetectable in extracts from rabbit accessory sex organs, testis, uterus, liver, lung, kidney and intestine); (2) it is age-dependent (undetectable in extracts from sexually immature rabbit epididymides); (3) its maintenance is testis-independent following its post-pubertal induction or activation; (4) it is primarily localized in the caput region of the epididymis; (5) it is inactivated by elevated temperature; (6) it is macromolecular in nature; (7) it is DNase- and RNase-resistant; (8) it is irreversibly inactivated by leupeptin, indicating that it is a protease; and (9) it is effective on unoccupied and occupied receptors.
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PMID:Structural conversion of cytosolic steroid receptors by an age-dependent epididymal protease. 391 13

Estrogen binding activity was investigated in the epididymis of the turtle, Chrysemys picta using DNA-cellulose affinity chromatography. A component binding estradiol-17 beta specifically with high affinity (Kd:8.0 X 10(-10) M) and limited capacity (20 fmol/mg protein) was demonstrated in the epididymal cytosol. In addition, binding of estradiol-17 beta was sensitive to excess (100-fold) diethylstilbestrol or natural estrogens (estradiol-17 beta, estrone, and estriol) but not to progesterone or androgens (testosterone and 5 alpha-dihydrotestosterone). The specific estrogen binding macromolecules eluted from DNA-cellulose columns sedimented at 4-5 S in linear 5-20% sucrose gradients. These characteristics suggest the presence of an estrogen receptor in this androgen target organ.
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PMID:Estradiol binding activity in epididymal cytosol of the turtle, Chrysemys picta. 688 62

Rat adipose tissues contain high-affinity, hormone-specific cytoplasmic estrogen receptors. If adipose tissues are actually estrogen target tissues, then it should be possible to demonstrate in vivo binding and retention of 17 beta-[2H]estradiol in adipose tissue cell nuclei, the putative subcellular site of steroid action. Gonadectomized rats were given an intravenous injection of 40 microCi (0.11 microgram) 17 beta-[2,4,6,7-3H]estradiol. Animals were then killed, and cell nuclei were isolated from hypothalamus and various fat pads. Cell nuclear levels of radioactivity peaked at 1 h in both hypothalamus and parametrial adipose tissue, but the peak cell nuclear concentration in the fat pad was more than twice that in hypothalamus. At 1 h, 89% of the adipose tissue nuclear radioactivity migrated with 17 beta-estradiol on thin-layer plates. Radioactivity was retained in cell nuclei for more than 6 h in both tissues. This cell nuclear binding was estrogen specific. Pretreatment with radioinert estrogens (17 beta-estradiol or R 2858) abolished cell nuclear 17 beta-[3H]estradiol uptake, but other steroids (progesterone, corticosterone, and 5 alpha-dihydrotestosterone) were without effect. Cell nuclear binding was found in all fat pads studied in both males and females. Levels were highest in parametrial (females) and epididymal (males) fat pads, the depots with the highest concentration of cytoplasmic estrogen receptor. There were no sex differences in cell nuclear binding. Taken together these findings provide strong support for the contention that 17 beta-estradiol could affect lipid metabolism and body fat content in part by direct action on adipose tissues.
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PMID:In vivo cell nuclear binding of 17 beta-[3H]estradiol in rat adipose tissues. 745 97

Estrogen binding sites (ER) were studied, using 17 beta-[3H]estradiol as the ligand, in epididymal or parametrial and subcutaneous adipose tissues of male and female hamsters. Compared with other mammalian fat deposits, intact male and female hamsters possess abundant estrogen binding sites with moderate affinity for estradiol and which occur as a single class of receptor in males but as two populations in females. The levels of estrogen receptors depend on both sex and tissue localization. In males, receptor densities are higher in both localizations when compared to those of females and ER are more abundant in superficial adipose deposits than in the deep fat tissue. In females, there are two estrogen binding populations; the one with the highest affinity is similar to the classical estrogen receptor and both populations are more abundant in deep fat than in subcutaneous deposits, in contrast to male hamsters. These characteristics depend on androgen status: in male adipose tissues, testosterone (TP) up-regulates the ER levels. Conversely, in female fat deposits, TP down-regulates the highest affinity estrogen receptors and the lowest affinity population disappears. Binding affinities are never affected by testosterone. These results suggest that, in hamster adipose tissue, estrogen receptors exhibit site- and sex-related differences, as previously described for androgen receptors. Furthermore, estrogen receptor expression is modulated by the androgen status, depending on gender, which could be related to some physiological situations observed in the hamster.
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PMID:Estrogen binding sites in hamster white adipose tissue: sex- and site-related variations; modulation by testosterone. 858 99

The reproductive system of male mice homozygous for a mutation in the estrogen receptor (ER) gene (ER knock-out; ERKO) appears normal at the anatomical level. However, these males are infertile, indicating an essential role for ER-mediated processes in the regulation of male reproduction. Adult ERKO male mice have significantly fewer epididymal sperm than heterozygous or wild-type males. Although spermatogenesis is occurring in some seminiferous tubules of 3- to 5-month-old ERKO males, other tubules either have a dilated lumen and a disorganized seminiferous epithelium with few spermatogenic cells or lack a lumen and contain mainly Sertoli cells. There are no obvious differences in seminiferous tubules at 10 days of age between wild-type and ERKO mice, but the lumen in ERKO males is dilated in all seminiferous tubules by 20 days. However, spermatogenesis progresses and similar numbers of sperm are present in the cauda epididymis of ERKO and wild-type males until 10 weeks of age. Disruption of spermatogenesis and degeneration of the seminiferous tubules become apparent after 10 weeks in the caudal pole of the testis and progresses in a wave to the cranial pole by 6 months. However, the seminal vesicles, coagulating glands, prostate, and epididymis do not appear to be altered morphologically in ERKO mice. Serum testosterone levels are somewhat elevated, but LH and FSH levels are not significantly different from those in wild-type males. Sperm from 8- to 16-week-old mice have reduced motility and are ineffective at fertilizing eggs in vitro. In addition, ERKO males housed overnight with hormone-primed wild-type females produce significantly fewer copulatory plugs than do heterozygous or wild-type males. These results suggest that estrogen action is required for fertility in male mice and that the mutation of the ER in ERKO males leads to reduced mating frequency, low sperm numbers, and defective sperm function.
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PMID:Targeted disruption of the estrogen receptor gene in male mice causes alteration of spermatogenesis and infertility. 889 49

Estrogen receptor mRNA expression was detected in the head and tail parts of the human epididymis by means of reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemical labelling showed that ciliate and nonciliate cells from the epithelium of the efferent ductules possessed strong to moderate nuclear staining for estrogen and progesterone receptors. The epididymal duct was negative for both antigens. Vascular endothelial cells also showed estrogen receptor, but no progesterone receptor immunolabelling in all regions of the organ. Immunoreactivity for the estrogen receptor-related antigen (ER-D5) was seen in the cytoplasm of ciliated and nonciliated epithelial cells from the efferent ductules, in the basal cells of some epididymal duct profiles as well as in myofibroblasts of the lamina propria, endothelial cells and smooth muscle cells of the vessel walls. The results obtained suggest that the epithelial cells of the efferent ductules of the human epididymis may be main target structures of estrogens and progestins.
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PMID:Estrogen and progesterone receptors and estrogen receptor-related antigen (ER-D5) in human epididymis. 921 30


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