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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracts of washed spermatozoa from hamster and guinea pig cauda epididymidis and of human ejaculated sperm were all found to stimulate the motility of unwashed hamster epididymal spermatozoa in vitro, and to support development of fertilizing ability. The motility of hamster spermatozoa was only sustained in the presence of both sperm extracts and appropriate energy substrates, indicating a synergistic effect of the motility-stimulating component of the sperm extracts with energy sources. Albumin was also required for the development of fertilizing ability by hamster sperm. Comparison of different combinations of energy substrates indicated that pyruvate was the most important energy source for sperm motility and the acrosome reaction, but glucose and lactate played suporting roles. In all 3 species examined, the component of the sperm extracts that was responsible for stimulating hamster sperm motility was found to be heat-stable and to have the same elution volume on a Sephadex G-10 column, with an estimated molecular weight of about 200. These properties are identical to those of the sperm motility-stimulating factor found in blood serum and adrenal gland, suggesting that the active components may be similar or possibly the same.
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PMID:The effects of sperm extracts and energy sources on the motility and acrosome reaction of hamster spermatozoa in vitro. 83 47

Cinnamon and Brewer's yeast extracts have been shown to potentiate the action of insulin in isolated adipocytes. In this study, isolated rat epididymal adipocytes were used to evaluate the influence of bovine serum albumin on insulin activity as affected by cinnamon and Brewer's yeast extracts. Albumin at 0.01-0.1% decreased the insulin stimulatory effects of cinnamon from 11.8- to 5.3-fold and 2% albumin decreased this effect to near control levels. Conversely, the insulin-enhancing properties of Brewer's yeast remained low in the presence of less than 0.25% albumin but subsequently increased 2.8-, 4.8- and 5.6-fold in the presence of 0.25, 0.50 and 1.0% albumin, respectively. In the absence of added insulin, increased activity of the insulin-stimulated utilization of glucose by both extracts was observed but only Brewer's yeast extract displayed additive effects when tested at higher insulin levels. Due to the inhibitory and enhancing effects of albumin on the insulin activity of cinnamon and Brewer's yeast, respectively, it is suggested that the effects of albumin be assessed when evaluating the insulin-enhancing effects of other substances using isolated adipocytes.
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PMID:Insulin activity: stimulatory effects of cinnamon and brewer's yeast as influenced by albumin. 129 75

Albumin reduces capillary permeability and acts as a carrier for various small molecules. Recently, we identified a 60-kDa sialoglycoprotein (gp60) on the surface of cultured rat microvascular endothelial cells (MEC) that binds albumin and antiglycophorin serum (alpha-gp). We verified that alpha-gp recognizes the albumin-binding gp60 by affinity, purifying proteins from MEC extracts using immobilized albumin. gp60 was immunoblotted with alpha-gp only when the MEC extract was reacted with albumin and not in controls. We immunoprecipitated gp60 from biosynthetically radiolabeled MEC lysates and from extracts containing endothelial surface proteins of isolated rat hearts that were radioiodinated in situ. gp60 was immunoblotted selectively in rat tissue microvascular beds lined with continuous endothelium (heart, lung, diaphragm, fat, skeletal muscle, mesentery, and duodenal muscularis but not cortical brain) and not those exclusively lined with fenestrated or sinusoidal endothelium (adrenal, pancreas, liver, and small intestinal mucosa). MEC isolated from rat heart, lung, and epididymal fat pad expressed gp60 and bound albumin, whereas various nonendothelial cells and brain-derived MEC did not. gp60 is an albumin-binding glycoprotein expressed specifically on the surface of continuous endothelium that binds albumin apparently not only to initiate its transcytosis via plasmalemmal vesicles but also to increase capillary permselectivity.
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PMID:gp60 is an albumin-binding glycoprotein expressed by continuous endothelium involved in albumin transcytosis. 173 16

Albumin enhances prostaglandin E2 (PGE2) binding to isolated epididymal adipocyte membrane and also binds PGE2 with low affinity. On the other hand, S-100, ovalbumin and albumin-stearate failed to bind PGE2, as shown by ultrafiltration, and also failed to enhance PGE2 binding to the isolated adipocyte membranes. These results suggested that albumin enhances PGE2 binding possibly by serving as a carrier for the prostaglandin molecules. 3 mM warfarin or 1 mM phenylbutazone inhibited PGE2 binding to albumin by 70% and 95%, respectively, but both drugs failed to affect the enhancement of PGE2 binding to the isolated adipocyte membrane in the presence of albumin. These results exclude the possibility that PGE2 bound to albumin is more accessible to the prostaglandin receptor than free PGE2 in solution. Finally it is shown that fatty acid binding protein (FABP), a cytosolic protein which binds specifically PGE1 but not PGE2, enhances PGE1 and PGE2 binding to isolated adipocyte membranes similarly to albumin. The physiological implications of these findings are discussed.
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PMID:Fatty acid binding protein (FABP) modulates prostaglandin E binding to rat epididymal adipocyte membrane similarly to albumin. 210 54

The addition of albumin to a suspension of plasma membranes isolated from rat epididymal fat cells increases both the initial binding rate and the maximal specific binding of prostaglandin E2 to these membranes. The presence of albumin affects neither the dissociation rate of bound prostaglandin E2 nor its dissociation constant. The results indicate that the interaction of albumin with the isolated membranes exposes latent prostaglandin-binding sites. Albumin fails to alter the specific binding of prostaglandin E2 to membranes isolated from frog erythrocytes or from rat peritoneal fat cells. These results indicate that the effect of albumin on the specific binding of prostaglandin E2 characterizes a specific molecular property of the prostaglandin receptors in rat epididymal adipocytes.
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PMID:Exposure of latent prostaglandin-binding sites in the rat epididymal adipocyte membrane. 287 Jul 37

The specific binding of rat serum albumin (RSA) to confluent microvascular endothelial cells in culture derived from the vasculature of the rat epididymal fat pad was studied at 4 degrees C by radioassay and immunocytochemistry. Radioiodinated RSA (125I-RSA) binding to the cells reached equilibrium at approximately 20 min incubation. Albumin binding was a slowly saturating function over concentrations ranging from 0.01 to 50 mg/ml. Specific RSA binding with a moderate apparent affinity constant of 1.0 mg/ml and with a maximum binding concentration of 90 ng/cm2 was immunolocalized with anti-RSA antibody to the outer (free) side of the endothelium. Scatchard analysis of the binding yielded a nonlinear binding curve with a concave-upward shape. Dissociation rate analysis supports negative cooperativity of albumin binding, but multiple binding sites may also be present. Albumin binding fulfilled many requirements for ligand specificity including saturability, reversibility, competibility, and dependence on both cell type and cell number. The results are discussed in terms of past in situ investigations on the localization of albumin binding to vascular endothelium and its effect on transendothelial molecular transport.
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PMID:Specific albumin binding to microvascular endothelium in culture. 327 21

Loss of forward motility of rabbit epididymal spermatozoa in high K+ phosphate buffer is inhibited by taurine, hypotaurine, epinephrine and bovine serum albumin. Pyruvate and lactate also show this effect. The rate of lipid peroxidation in these spermatozoa, as measured by rate of formation of malondialdehyde, is also inhibited by these agents. A close linear correlation between percent inert spermatozoa and malondialdehyde was found, which was independent of the rate of peroxidation. Complete cessation of motility was observed at 0.5 nmol malondialdehyde/10(8) cells in the absence or presence of these agents, which is the same value found in other suspending media in a previous study [Alvarez and Storey (1982) Biol. Reprod. 27:1102-1108]. Albumin was the most effective agent in preventing loss of motility and inhibiting lipid peroxidation. Hypotaurine was the next most effective, followed by taurine, epinephrine, pyruvate and lactate. Hypotaurine reduces the amount of rate of superoxide production, as measured by the rate of reduction of acetylated ferricytochrome c by O(2), from rabbit sperm under these conditions and concomitantly reduces inactivation of the superoxide dismutase in these cells. Since superoxide seems to be the major inducer of lipid peroxidation in rabbit sperm, the protective effect of hypotaurine, which should be readily permeant to the plasma membrane, may be ascribed to scavenging of intracellular superoxide. The mechanism of the protective action of albumin is not known. Rabbit epididymal spermatozoa lose motility over time if Ca2+ or Mg2+ are omitted from the suspending medium.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Taurine, hypotaurine, epinephrine and albumin inhibit lipid peroxidation in rabbit spermatozoa and protect against loss of motility. 662 44

The proteins of epididymal luminal fluid and of spermatozoa recovered from different regions of the rat epididymis were examined by polyacrylamide gel electrophoresis under non-denaturing and denaturing conditions. Albumin (A) and four major pre-albumin bands (B-E) were observed in epididymal fluid from the cauda on non-denaturing gels. By comparing the migration of these bands with that of standard globular proteins on denaturing gels, the molecular weight of Bands B and C was estimated to be 16 000, Band D was 30 000 and Band E was 32 000. Bands D and E were apparently glycoproteins since they stained with periodic acid-Schiff's reagent and were bound by an affinity column of Concanavalin A. The pre-albumin proteins (B-E) were of epididymal origin since they (a) were not detected in blood serum, (b) were not detected in testicular extracts and (c) were still found after ligation of the efferent ducts. From the incorporation of radioactive methionine, Bands B and C were shown to be synthesized in the initial segment and caput. The regional distribution of luminal proteins indicated that protein D was added in the caput and cauda and protein E in the cauda. This regional origin of luminal proteins was confirmed by the altered protein profiles consequent upon the reduced fluid flow through the epididymis brought about by ligation of the efferent ducts. The androgen-dependence of epididymal protein synthesis was also investigated using radioactive methionine. Castration had little effect on total protein synthesis but resulted in the specific reduction of the synthesis of proteins B and C. Several changes were observed in the relative amounts of specific proteins extracted from spermatozoa from different regions of the epididymis and several of these proteins had molecular weights identical with those in luminal fluid. However, there was no evidence for any substantial binding to spermatozoa of the pre-albumin proteins (B-E) of luminal fluid.
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PMID:Characterization and androgen-dependence of proteins associated with luminal fluid and spermatozoa in the rat epididymis. 743 Dec 93

Effect of albumin on proluminal androgen movement from the peritubular space to the intratubular fluids of the adult rat testis and epididymis was examined by using in vivo microperifusion and subsequent micro-puncture of the seminiferous tubules and caput epididymal tubules. Tubules were perfused with four different fluids: (1) Minimum Essential Medium (MEM) containing 3H-testosterone and 14C-polyethyleneglycol (PEG) alone; (2) MEM + 8 mg/ml Bovine Serum Albumin (BSA) containing the same radiolabeled compounds as above; (3) MEM + 80 mg/ml albumin containing the same radiolabeled compounds as above; and (4) Testosterone-free rat serum containing the same radiolabeled compounds as above. Bound 3H-androgens in the interstitial fluids of the testis and epididymis after one-hour perifusion with the four different fluids above were measured by charcoal assay. In the testis, proluminal 3H-androgen movement was not significantly altered by addition of albumin to the perifusion fluid (p = 0.08). Bound 3H-androgens in the interstitial fluid after perifusion were significantly increased with increasing albumin concentrations in the perifusion fluid. In the caput epididymis, proluminal 3H-androgen movement was significantly decreased with increasing albumin concentration in the perifusion fluid. Bound 3H-androgens in the interstitial fluid after perifusion were significantly increased with increasing albumin concentrations in the perifusion fluid (p < 0.05). These findings suggest that proluminal transepithelial movement of 3H-androgens in the reproductive tract could be influenced by the presence of albumin, androgen-binding protein or some other binding protein in the peritubular space.
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PMID:Effect of albumin on proluminal movement of 3H-androgen into seminiferous and epididymal tubules and androgen binding in the interstitium of the testis and epididymis after perifusion with fluid containing albumin. 789 69

Albumin is the major carrier of long chain free fatty acids, that are known to be heavily utilized by fat cells. To investigate the cellular structures involved in the interaction of albumin with preadipocytes, precursor fat cells isolated from rat epididymal fat pads were cultured in Dulbecco's modified Eagle's medium supplemented with 5% fetal calf serum and antibiotics. Cell differentiation was induced by 1.7 nM insulin added to the culture medium. The ensuing cells in various stages of differentiation were incubated with albumin, alone or bearing oleic acid, adsorbed to 5 nm gold particles (Alb-Au or Alb-OA-Au) for 10 min at 37 degrees C. As control, polyethyleneglycol-gold and IgG-gold complexes were used in same conditions. After extensive washing, the cell monolayer was fixed in 2.5% glutaraldehyde, and processed for electron microscopy. Examination of thin sections and morphometric analysis showed that: a) in the process of adipogenesis induced in vitro four cell types were simultaneously present: fibroblast-like cells (F), early adipocytes (EA), adipocytes (A) and aged adipocytes (AA); b) upon incubation with Alb-Au, the probe labelled preferentially coated pits and coated vesicles and only some uncoated vesicles; in time the tracer was found in endosomes, occasionally, multivesicular bodies and lysosome-like structures. The binding and uptake was dependent on the stage of cell differentiation, being less pronounced in fibroblast-like cells and increased in later stages (A and AA); c) Alb-OA-Au labelled the same structural features like the Alb-Au (i.e. coated pits and vesicles); however, the binding to the cell membrane was fourfold higher than that of Alb-Au in F and EA stages and was maintained at the same level in A and AA stages; d) control probes were taken up only by adipocytes and aged adipocytes, cells that express a strong phagocytic function for all tracers used. These results indicated that albumin bound to gold and especially albumin-bearing fatty acids-gold, bind preferentially to coated pits and vesicles of preadipocytes. Further internalization of albumin-gold particles seems to be non-specific, since both the probes and the controls adsorbed to gold were delivered to the same endosomal-lysosomal compartment.
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PMID:Cellular structures involved in albumin interaction with preadipocytes in various stages of adipogenesis, in vitro. 801 43


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