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

An apparently specific glutathione oxidase activity is present in renal cortex, epididymal caput, jejunal villus tip cells, choroid plexus, and retina (but not in liver). The activity is membrane-bound and is localized on the luminal surface of the brush border membranes of the kidney and jejunum. The distribution and localization of the oxidase are similar to those of gamma-glutamyl transpeptidase, suggesting that there is a significant relationship among the translocation of intracellular glutathione, the extracellular oxidation of glutathione to glutathione disulfide, and the reactions of the gamma-glutamyl cycle. Thus, both glutathione present in the blood plasma and intracellular glutathione translocated to the cell surface are accessible to oxidation and transpeptidation. Acceptor substrates of the transpeptidase (e.g., L amino acids) promote transpeptidation and decrease oxidation of glutathione. Conversion of glutathione to glutathione disulfide is followed by utilization of the latter compound by gamma-glutamyl transpeptidase and dipeptidase. Although intracellular oxidation of glutathione to glutathione disulfide is readily reversed by the action of glutathione reductase, glutathione disulfide formed extracellularly cannot be reduced; instead, it undergoes hydrolytic and transpeptidation reactions leading to gamma-glutamyl amino acid and amino acid products which may be recovered by being transported into the cell.
 ...
PMID:Conversion of glutathione to glutathione disulfide by cell membrane-bound oxidase activity. 3 3

The distribution of shared antigens in specialized surface membranes of epithelia associated with absorption and excretion was studied using antisera against isolated epithelial brush borders of renal proximal tubules. Rabbits were immunized with a membrane fraction isolated from rat kidneys and the reactions of the resulting heterologous antisera with different rat organs were studied by immunofluorescence. The antisera reacted with the following structures: epithelial brush border of renal proximal tubules, bile canaliculi and bile duct epithelium of the liver, epithelial brush border of the intestinal villi, luminal parts of some epididymal tubules, allantochorionic epithelium, and apical parts of the exocrine epithelium of the pancreatic, salivary and lacrimal glands. Both quantitative and qualitative differences in antigen contents were suggested by absorption experiments.
 ...
PMID:Membrane antigens shared by renal proximal tubules and other epithelia associated with absorption and excretion. 78 15

The general histology and ultrastructural features of the developing ductus epididymidis were examined in the brown marsupial mouse, Antechinus stuartii, from April, when males were sexually immature, until August, when the adult males were involved in mating activities, just prior to the annual male die-off. Samples were also examined 3 and 6 months after the August die-off period in males kept in isolation from conspecifics during the prebreeding and breeding periods. In April, tubule diameter and epithelial height were largest in the caput and least in caudal segments but the reverse was observed thereafter. Epithelial height increased in caput segments in August and remained high in the post die-off samples. However, caput epithelial height and tubule diameters were low compared with the remainder of the duct from July until February. Luminal shape in caudal segments (10, 11 and 12) changed in June from circular to a narrow slit, and the epithelium became variable in height. The epididymal epithelium was undifferentiated with few cytoplasmic organelles in April. Differentiation occurred mostly from May to June in association with an increased abundance of cytoplasmic organelles, increasing prostatic weight and rising plasma androgen levels. Differentiated principal and basal cells were found in caput and corpus regions in May and in caudal segments in June in association with the de novo development of a brush border of microvilli. Few clear cells were seen in caput and corpus regions of the duct in May but they, and mitochondria-rich cells, were common throughout the duct from June. Development of the unusual structural features of the cauda epididymidis preceded the arrival of spermatozoa in June. The presence of degenerating spermatozoa and cytoplasmic droplets in the cauda at this time suggested that it was not yet capable of supporting sperm viability. There was no evidence to suggest that the presence of spermatozoa has a stimulatory effect on the epididymis. Intact sperm were observed throughout the duct from July. Free cytoplasmic droplets, which showed some evidence of degeneration, collected in large masses in the distal corpus/proximal cauda epididymidis of adult males between aggregates of spermatozoa. Epididymal differentiation appeared complete by mid-July; few ultrastructural changes occurred after this time. Recruitment of spermatozoa into the epididymis ceased by August and was associated with a rapid decline in sperm content in the proximal caput segments. In the November and February samples, spermatozoa were present only in distal corpus and proximal cauda segments.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Late postnatal development and differentiation of the ductus epididymidis in a dasyurid marsupial (Antechinus stuartii). 141 75

The localization of immobilin, a glycoprotein known to be present and to immobilize spermatozoa in the lumen of the epididymis, was investigated using light and electron microscope immunocytochemistry. In the light microscope, a distinct immunoperoxidase reaction product was observed in the lumen over the brush border of the epithelial nonciliated cells of the efferent ducts, while only a faint reaction was seen over their supranuclear region. In the proximal area of the initial segment of the epididymis no immunoperoxidase staining was observed either over epithelial cells or in the lumen. In the middle area of the initial segment, several epithelial principal cells became intensely immunostained but the majority were unstained; a weak reaction appeared in the lumen. In the distal area of the initial segment, more principal cells became immunostained, and while some were intensely reactive, others were moderately or weakly stained or unreactive. In the intermediate zone and proximal caput epididymidis, the principal cells showed the maximal immunoreactivity with all principal cells being reactive; staining in the lumen also reached its maximal reactivity in these areas. Immunostaining of principal cells gradually decreased along the epididymal duct and disappeared in the cauda epididymidis, however, an intense reaction persisted in the lumen. In the distal area of the cauda epididymidis, clear cells were reactive. In the electron microscope, immunogold labeling of reactive principal cells of the middle and distal areas of the initial segment, intermediate zone, and caput epididymidis was detected over cisternae of endoplasmic reticulum, stacks of Golgi saccules, and spherical electron lucent (200-400 nm in diameter) vesicles. The latter were present on the trans face of the Golgi stack, in the vicinity of th Golgi apparatus, and close to the apical cell surface; they are considered as secretory vesicles involved in the secretion of immobilin. In the distal area of the cauda epididymidis, epithelial clear cells showed an intense immunogold labeling over their endocytic apparatus. Immunogold labeling in the lumen of the epididymis was found over a fine flocculent material dispersed between the sperm. This material was especially abundant in the cauda epididymidis and did not appear to be bound to the surface of the sperm. The present results suggest that principal cells of the epididymis are involved in the secretion of immobilin, but that a differential secretory pattern exists between epididymal segments with maximal secretory activity occurring in the intermediate zone and proximal caput epididymidis, while no secretion takes place in the cauda epididymidis. Excess immobilin appears to be endocytosed for degradation by clear cells of the cauda epididymidis.
 ...
PMID:Epithelial cells of the epididymis show regional variations with respect to the secretion of endocytosis of immobilin as revealed by light and electron microscope immunocytochemistry. 154

The seminal marker of epididymal function alpha-1, 4-glucosidase was localized histochemically in the cytoplasm of the efferent duct epithelium and the brush border of the entire length of the human epididymis. Quantification using the specific inhibitor castanospermine revealed strongest activity in the corpus and cauda regions. Selective inhibition of the brush border enzyme activities by maltotriose identified these as the neutral isoenzymes. Despite detection of alpha-glucosidase in the renal tubules of all the animals studied, the enzyme was not detectable in epididymides of hamsters or mice. In rabbits and monkeys, it was absent from the entire brush border but present weakly in the cytoplasm of the proximal epididymides. An enzyme distribution pattern similar to that in the human epididymis was found in rats, except for the absence of histochemical staining at pH 6.5 from the initial segment and distal cauda epididymidis. Experiments in which endogenous testosterone was depleted in rats demonstrated the dependence of epididymal alpha-glucosidase on androgen, albeit with a low sensitivity. This study suggests the rat to be a suitable model for the investigation of the role of epididymal alpha-glucosidase in fertility.
 ...
PMID:Histochemical localization and quantification of alpha-glucosidase in the epididymis of men and laboratory animals. 211 30

5-Br-4-Cl-3-Indoxyl-alpha-D-gluco(pyrano)side was found to be the most suitable synthetic substrate for the demonstration of alpha-D-glucosidases in situ. Using an azoindoxyl procedure with hexazotized pararosaniline or new fuchsine at pH 5 in freeze-dried celloidine-mounted cryostat sections acid alpha-D-glucosidase (EC 3.2.1.20) was shown for the first time in lysosomes of many cells of fetal and adult rat, mouse, guinea-pig, marmoset and human organs. At pH 6.5, in chloroform-acetone pretreated cryostat sections plasma membrane alpha-D-glucosidases were shown in the brush border of enterocytes of the small and large intestine, in the brush border of proximal renal tubule cells and in the stereocilia of the epididymal duct. In an indigogenic procedure with ferricyanide/ferrocyanide as redox catalysator plasma membrane alpha-D-glucosidases were depicted as well as with the azo-indoxyl method; the demonstration of the acid alpha-D-glucosidase was inferior to that achieved with the azo-indoxyl procedure. Using tetrazolium salts as capture reagent intracellular localization was unsatisfactory. In enterocytes, a localization in the Golgi apparatus was shown by the azo-indoxyl procedure only. Analytical isoelectric focusing revealed organ-dependent differences of plasma membrane and lysosomal alpha-D-glucosidases. Compared with the already existing methods the azo-indoxyl and indigogenic procedures are by far the most suitable techniques.
 ...
PMID:Histochemical detection of alpha-D-glucosidases and their molecular forms with 5-Br-4-Cl-3-indoxyl-alpha-D-glucoside. 310 70

Sperm maturation and storage occur in a unique milieu created in large part by the epididymal epithelium. To learn more about the interaction of the epididymal epithelial cell with both luminal and systemic environments, we now report on the preparation and characterization of epididymal epithelial cell plasma membranes. A preparation enriched for epididymal epithelial cell plasma membranes was isolated from collagenase-digested epididymal tubule fragments by hand-Dounce homogenization, differential centrifugation, and sucrose gradient centrifugation. The final membrane fraction was enriched 11-fold for the plasma membrane marker 5'-nucleotidase; 2.6-fold for the lysosomal marker acid phosphatase, and 3-fold for the Golgi marker thiamine pyrophosphatase. No enrichment was observed for mitochondrial or endoplasmic reticulum enzyme markers. Specific and saturable transferrin-binding activity was also detected in the final preparation. Electron microscopy revealed the presence of vesicles and sheets of membranes as well as an occasional Golgi apparatus. The plasma membrane fraction was used to generate monoclonal antibodies. Of 102 wells exhibiting growth, 12 were positive by immunofluorescent staining of frozen sections. Ten of these recognized determinants in epithelial cells, and 2 stained peritubular smooth muscle cells. Most of the epithelial cell-specific antibodies stained brush border alone or in combination with the basolateral plasma membrane. Three antibodies stained the Golgi apparatus. Most antibodies were specific for particular epididymal regions, 3 also recognized determinants in the kidney, and 1 stained residual bodies in the testis.
 ...
PMID:Isolation and characterization of epididymal epithelial cell plasma membranes. 336 69

The pathogenicity of highly purified brush border membrane (BBM) antigens in Heymann Nephritis was compared to that of a crude renal tubular Fx1A preparation and was found to be equally pathogenic. Both antigen preparations induced formation of autologous antisera. Double immunodiffusion studies demonstrated a reaction of identity between anti-BBM and anti-Fx1A antisera. Both antisera detected the same number of antigenic components when reacted against BBM or Fx1A preparations. When antibody was eluted from the kidneys of rats with Heymann nephritis it reacted in vitro with the renal BBM as shown by indirect immunofluorescence. Eluted antibody also cross reacted with epididymal tubules, but not with other epithelia, showing that the pathogenic antigens have a restricted tissue distribution. Heymann nephritis was readily induced in rats, but could not be induced in dogs, suggesting a species difference in susceptibility to this form of nephritis. Injection of heterologous anti-BBM or anti-Fx1A antisera resulted in rapid localization to the GBM in a granular pattern, suggesting reaction with circulating antigen or in situ immune complex formation with native or planted glomerular components. Rats with aminonucleoside nephrosis showed BBM localization of injected heterologous antisera, demonstrating their specificity in vivo. Our data provide a rationale for using purified BBM antigens for the production of a homogeneous model of Heymann nephritis.
 ...
PMID:Pathogenicity of a highly purified brush border membrane preparation in Heymann nephritis. 645 9

The activity of epididymal alpha-glucosidase in adult rats was rapidly suppressed to histochemically undetectable levels within 2 days by the continuous release of the enzyme inhibitor castanospermine via a peritoneal osmotic pump at a rate of 100-200 nmol h-1. It was established that mating activities overnight depleted 72% of the spermatozoa in the distal cauda, which was replenished in 2 days, and that fertility began to decline 3 weeks after efferent duct ligation. Male rats of proven mating proficiency and fertility were treated with castanospermine, or buffered saline as control, for up to 30 days and enzyme inhibition was confirmed at the end of treatment by histochemistry. Fertility was normal at the first mating test on day 7, significantly decreased at the second mating on day 9, but recovered in a stepwise manner at subsequent matings on days 12 and 14. Delaying the third mating until day 25 did not sustain the transient subfertility. However, prolonging sperm storage in the distal cauda epididymides and preventing replenishment with freshly matured spermatozoa, by efferent duct ligation for 14 days performed on day 15 during castanospermine administration, caused a decrease in fertility and a change in the kinematics of epididymal spermatozoa of the castanospermine-treated group. In control rats, binding of epididymal spermatozoa to Vicia faba, a lectin specific for glucose and glucosamine, and mannose and mannosamine residues, decreased from the proximal caput to the distal corpus coincident with the increase in alpha-glucosidase activity on the epithelial brush border. Lectin binding then increased in the cauda where enzyme activity was absent. However, castanospermine treatment did not significantly alter this binding profile. The findings suggest that epididymal alpha-glucosidase does not play a crucial role in the development of sperm fertilizing capacity, but may be involved in the preparation of spermatozoa for storage.
 ...
PMID:Study of the role of epididymal alpha-glucosidase in the fertility of male rats by the administration of the enzyme inhibitor castanospermine. 786 94

Angiotensin converting enzyme exists in two different isoforms, somatic and germinal, whose respective distributions and intracellular localizations have not been precisely determined. The differing biochemical and molecular characteristics of the two isozymes allowed the preparation of antibodies specific for each of the two angiotensin converting enzyme isoforms and of two nucleic acid probes, one of which was specific for the germinal isoform. Immunohistochemistry and in situ hybridization were used to determine the cell distribution of, respectively, the two isoforms and their corresponding messenger RNAs in the classically studied tissues of male adult humans and marmosets. Results provided by the two different methods were always concordant and were identical in the two species. The somatic angiotensin converting enzyme form was expressed uniquely in somatic tissues (vascular endothelial cells and at the brush border of renal proximal convoluted tubule, jejunal villus, and epididymal duct epithelia), and the germinal form was expressed uniquely in germinal cells with a precise stage-specific pattern, starting in round spermatids and finishing in spermatozoa. In situ hybridization documented the presence of somatic angiotensin converting enzyme messenger RNA in renal tubule epithelium, jejunal enterocytes, and epididymal epithelium and demonstrated that there was no direct correlation between the levels of angiotensin converting enzyme messenger RNA and the enzyme it encodes for, i.e., angiotensin converting enzyme, in a given epithelium. The significance of the ultraselective expression of germinal angiotensin converting enzyme and of its specific messenger RNA at a very precise stage of spermatogenesis remains uncertain.
 ...
PMID:Gene expression and tissue localization of the two isoforms of angiotensin I converting enzyme. 838 57


1 2 Next >>