UNIPROT:P56851 - FACTA Search

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

Epididymal maturation is essential for mammalian sperm to develop fertility. Wheat germ agglutinin (WGA), a lectin which specifically recognizes N-acetyl-glucosamine and sialic acid, was used to investigate membrane characteristics of epididymal sperm in the mouse. Histochemical and cytochemical localization revealed that WGA-binding sites were increased as sperm became mature. The binding sites were mainly localized in the plasma membrane of the anterior acrosome and tails. On Western blots of NP-40 extracts, two WGA-binding glycoproteins, GP-49 and GP-83, were identified on the sperm recovered from both corpus and cauda epididymidis. GP-83 was removed from the sperm surface by centrifugation and resuspension in phosphate-buffered saline (PBS) three times. GP-49 was resistant to centrifuging at 400 g for 5 min up to seven times and the treatment with 1M NaCl in PBS. These observations suggest that GP-49 is very likely an intrinsic membrane protein of the sperm, whereas GP-83 is an extrinsic protein.
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PMID:Identification of two maturation-related, wheat-germ-lectin-binding proteins on the surface of mouse sperm. 172 60

Two alpha-D-mannosidases have previously been identified in rat epididymis. This communication reports the purification and characterization of the "acid" alpha-D-mannosidase. The enzyme was purified over 1000-fold to near homogeneity by acetone and (NH4)2SO4 precipitation followed by ion-exchange and hydroxylapatite chromatography. The molecular weight of the enzyme was estimated to be 220,000 by gel filtration. Polyacrylamide gel electrophoresis of the native enzyme under two conditions of buffer and pH showed a single band when stained for protein while electrophoresis under denaturing conditions resulted in bands of apparent Mr 60,000 and 31,000. The enzyme is a glycoprotein containing about 5.6% hexose. In addition to mannose (3.1%) and glucosamine (2.0%), the enzyme also contained small amounts of glucose, fucose, and galactose. Chemical analysis indicated the absence of sialic acid. The substrate specificity of the purified enzyme was investigated using linear and branched mannose-containing oligosaccharides. The enzyme cleaved linear oligosaccharides [Man(alpha 1-2)Man(alpha 1-2)Man(alpha 1-3)Man(beta 1-4)GlcNAc and Man(alpha 1-2)Man(alpha 1-3)Man(beta 1-4)GlcNAc] very efficiently. However, little or no activity was observed toward high mannose oligosaccharides (Man9GlcNAc through Man5GlcNAc) or the branched trimannosyl derivative Man3GlcNAc. This specificity is very similar to that observed with rat kidney lysosomal alpha-D-mannosidase. Additional evidence that the epididymal enzyme is essentially a lysosomal alpha-D-mannosidase is the fact that polyclonal antibody prepared against the purified epididymal enzyme cross-reacted with lysosomal alpha-D-mannosidase from several rat tissues and with acidic alpha-D-mannosidase of a human cell line, results suggesting that the antibody will be useful in studying the biosynthesis and turnover of lysosomal alpha-D-mannosidases in at least two species.
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PMID:Rat epididymal alpha-D-mannosidase: purification, carbohydrate composition, substrate specificity, and antibody production. 319 37

Protein synthesis in epididymal tissue of intact and castrated rabbits was studied after incubation of epididymal minces with [35S]-cysteine or [35S]-methionine and protein separation by two-dimensional gel electrophoresis. Regional differences in the pattern of protein synthesized were observed. Castration did not change overall protein synthesis, but it reduced these regional differences. The presence of 5 alpha-DHT in the culture medium of the proximal corpus epididymidis perfused for 24 hr did not increase overall protein synthesis in tubules from intact or castrated rabbits and did not reinitiate synthesis of the proteins that had disappeared after castration. The kinetics of glycoprotein synthesis and secretion were studied by light and electron microscopy autoradiography at 0.5, 2, 6, and 24 hr after exposure to [3H]-mannose, [3H]-fucose, and [3H]-glucosamine. Changes in the distribution of mannose- and glucosamine-labeled material indicated that the decline in grain density over the epithelium from 30 min to 24 hr coincided with an increasing reaction over the stereocilia border from 30 min to 2 hr and in the lumen from 2 to 24 hr. The distribution of fucose-labeled material indicated that the grain reaction over the epithelium declined more rapidly than with the mannose label. When the glucosamine-labeled sperm mass was released from the tubules, the labeled material was lost after the first washing, indicating that the glucosamine-labeled glycoproteins did not bind firmly to corpus spermatozoa within 24 hr. After castration, both mannose- and fucose-labeled materials migrated to the cell apex more rapidly than in the intact animal, but they were not released as readily into the lumen. The culture of epididymal tubules from castrated males with 5 alpha-DHT for 24 hr did not promote the release of either mannose- or fucose-labeled material into the lumen. However, testosterone given in vivo for 2 weeks restored secretion of mannose-labeled material into the lumen.
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PMID:Secretion of proteins and glycoproteins by perifused rabbit corpus epididymal tubules: effect of castration. 366 63

Maturation of the spermatozoon of the common marmoset (Callithrix jacchus) during epididymal transit was investigated using light and electron microscopy. Except for the caudal migration of the cytoplasmic droplet there were no apparent ultrastructural modifications, although interesting morphological features of the sperm head were observed such as the substructure of the acrosome and a waist at the equatorial region. Alteration to the plasmalemma during maturation was reflected by an increasing capacity of the sperm surface to bind wheat germ agglutinin (recognising n-acetyl-d-glucosamine) but not ricin communis or concanavalin agglutinins. This change was concomitant with the development of sperm fertilising capacity in this species.
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PMID:The structure and epididymal maturation of the spermatozoon of the common marmoset (Callithrix jacchus). 632 76

The localization of glycoprotein synthesis and storage was studied during acrosome formation in guinea-pig using fine-structure autoradiography after (3H)-fucose incorporation. Three days after (3H)-fucose injection, labelling in spermatids was concentrated in the matrix of developing acrosomes, and it was evident that the fucosylation of acrosomal glycoproteins largely overshadowed the fucosylation of other spermatid glycoproteins. Acrosin labelling and its quantitative relation to labelling of other glycoproteins was examined in mature rabbit spermatozoa after incorporation of (14C)-fucose or (14C)-glucosamine during spermatogenesis. Cauda epididymis spermatozoa recovered 21 days after intratesticular application of (14C)-fucose or (14C)-glucosamine were analysed for acrosin specific labelling after acid extraction and gel filtration. In all the material examined, radioactivity was detected in the proacrosine fractions; radioactivity in purified proacrosin amounted to at least 2% of the total radioactivity in the epididymal sperm population. In addition to the peak with radioactive proacrosin, another radioactive peak in (14C)-glucosamine-labelled material was attributed to a glycoprotein intraacrosomal inhibitor of acrosin. It is concluded that (pro)acrosin (acrosin-inhibitor) complexes seem to contribute significantly to acrosomal glycoprotein labelling by radioactive sugars and that the distribution of these complexes may at least correspond to their cytochemically detectable component, acrosin. The superposition of the distribution of acrosin and of other acrosomal glycoproteins during acrosome reaction can be explained by the fact that the dispersal of most of the acrosomal content is linked to proacrosin activation.
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PMID:Studies on acrosome labelling of mammalian spermatozoa by radioactive sugars. 643 21

We have studied the synthesis of protein-bound carbohydrates in differentiating male germ cells in the mouse. Spermatocytes and spermatids synthesize asparagine-linked and high-molecular-weight glycopeptides as the major classes of protein bound carbohydrates. Asparagine-linked glycopeptides were found to be mainly composed of the complex bi-antennary type as shown by affinity chromatography on concanavalin-A Sepharose; high-molecular-weight glycopeptides were represented by nonfucosylated lactosaminoglycans since they were metabolically labeled with [14C]glucosamine but not with [3H]fucose, did not bind to DEAE-cellulose, and were susceptible to endo-beta-galactosidase. Labeling with galactose oxidase/Na B3H4 technique demonstrated that lactosaminoglycans were present on the surface of differentiating germ cells and of testicular and epididymal spermatozoa. Since lactosaminoglycans from germ cells and testicular spermatozoa were not retained on a column of fucose-binding lectin, it was concluded that these molecules do not contain fucose. On the other hand, epididymal spermatozoa lactosaminoglycans bound to the lectin and therefore contained fucose. A soluble fucosyltransferase, capable of transferring fucose to germ cell lactosaminoglycans, was found to be present in the epididymis but not in the testis. These data show that developing germ cells synthesize nonfucosylated lactosaminoglycans which are probably preserved throughout spermiogenesis. We suggest that these molecules are fucosylated in vivo by a fucosyltransferase secreted by the epididymal epithelium.
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PMID:Lactosaminoglycans synthesized by mouse male germ cells are fucosylated by an epididymal fucosyltransferase. 670 6

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.
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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

We determined the effect of infusion of glucosamine (GlcN), which bypasses the rate limiting reaction in the hexosamine pathway, on insulin-stimulated rates of glucose uptake and glycogen synthesis in vivo in rat tissues varying with respect to their glutamine:fructose-6-phosphate amidotransferase (GFA) activity. Three groups of conscious fasted rats received 6-h infusions of either saline (BAS), insulin (18 mU/kg x min) and saline (INS), or insulin and GlcN (30 micromol/ kg x min, GLCN). [3-(3)H]glucose was infused to trace whole body glucose kinetics and glycogen synthesis, and rates of tissue glucose uptake were determined using a bolus injection of [1-(14)C]2-deoxyglucose at 315 min. GlcN decreased insulin-stimulated glucose uptake (315-360 min) by 49% (P < 0.001) at the level of the whole body, and by 31-53% (P < 0.05 or less) in the heart, epididymal fat, submandibular gland and in soleus, abdominis and gastrocnemius muscles. GlcN completely abolished glycogen synthesis in the liver. GlcN decreased insulin-stimulated glucose uptake similarly in the submandibular gland (1.3 +/- 0.2 vs. 2.0 +/- 0.3 nmol/mg protein x min, GLCN vs. INS, P < 0.05) and gastrocnemius muscle (1.4 +/- 0.3 vs. 3.1 +/- 0.5 nmol/mg protein x min), although the activity of the hexosamine pathway, as judged from basal GFA activity, was 10-fold higher in the submandibular gland (286 +/- 35 pmol/mg protein x min) than in gastrocnemius muscle (27 +/- 3 pmol/mg protein x min, P < 0.001). These data raise the possibility that overactivity of the hexosamine pathway may contribute to glucose toxicity not only in skeletal muscle but also in other insulin sensitive tissues. They also imply that the magnitude of insulin resistance induced between tissues is determined by factors other than GFA.
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PMID:Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance in multiple insulin sensitive tissues. 916 41

Heparin-binding proteins (designated BHB-2-BHB-9) were isolated from boar seminal plasma by affinity chromatography on heparin immobilized on polyacrylamide gel, followed by reverse phase HPLC. According to their N-terminal amino acid sequences, BHB-3-BHB-5 belong to the AQN family of spermadhesins and BHB-7-BHB-9 to the AWN family. BHB-6 is composed of two different proteins. The dominant protein (14 kDa) has the N-terminal amino acid sequence HNKQEGRDHD that is identical to the sequence of human semenogelin at positions 85-94. The minor proteins (16 and 17 kDa) belong to the AWN family of spermadhesins. The 14 kDa HNK protein does not crossreact with antibodies against AQN or AWN spermadhesins. BHB-2 also binds to the acrosome of boar epididymal spermatozoa but has the N-terminal sequence DQH. Therefore, basic protein BHB-2 belongs to a new family of DQH sperm surface proteins that are homologous to the acidic proteins from bull and stallion seminal plasma, to the collagen binding domain II in fibronectin and to the leucocyte cell-cell adhesion regulator, but are not homologous to AQN or AWN spermadhesins. Nevertheless, anti-AQN-1 spermadhesin antibodies crossreact strongly with DQH protein. All boar heparin-binding proteins bind concanavalin A indicating their glycoprotein nature, which was proved by the detection of glucosamine and galactosamine residues in their molecules. Furthermore, spermadhesins interact with zona pellucida, protease inhibitors and a polyacrylamide derivative of heparin. Affinity chromatography experiments showed that the DQH protein bound to gelatin-agarose together with the AWN proteins and that the DQH protein and AQN-1 spermadhesin belong to the phosphoryl choline binding proteins.
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PMID:Spermadhesins of the AQN and AWN families, DQH sperm surface protein and HNK protein in the heparin-binding fraction of boar seminal plasma. 987 52

The transcription factor CCAAT/enhancer-binding protein-alpha (C/EBPalpha) is a positive modulator of transcription for several adipocyte-specific genes that play a role in energy metabolism. However, there is little information available regarding the regulation of its expression by metabolic signals. Exposure to insulin for 5-24 h attenuated C/EBPalpha expression when 3T3-L1 adipocytes were incubated in 24 mM glucose, but not in 5.7 mM glucose. Nuclear run-on transcription assays indicated a transcriptional repression of C/EBPalpha gene, but not that of C/EBPbeta. Glucosamine, a product of the hexosamine pathway, in the presence of low glucose mimicked high glucose's ability to reduce C/EBPalpha messenger RNA expression in insulin-treated cells. Similar results were obtained with xylitol, an activator of the pentose phosphate pathway. There was no correlation between the accumulation of hexosamine pathway metabolites (e.g. UDP-N-acetylhexosamines) and/or changes in intracellular protein glycosylation with the ability of high glucose, glucosamine, or xylitol to down-regulate C/EBPalpha gene expression. None of these treatments caused a reduction in intracellular ATP levels. Stable transfection of 3T3-L1 cells with the 5'-flanking 468-bp sequence of the mouse C/EBPalpha gene fused to luciferase demonstrated that promoter activity was also reduced by these nutrients. Of interest, treatment of rats with glucose or glucosamine led to a reduction in C/EBPalpha messenger RNA levels in epididymal, but not omental, fat. Taken together, these results suggest that metabolic signals serve to down-regulate C/EBPalpha expression both in vitro and in vivo.
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PMID:Modulation of CCAAT/enhancer-binding protein-alpha gene expression by metabolic signals in rodent adipocytes. 1038 83

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