Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mammalian sperm-zona pellucida (ZP) interaction is mediated by sperm lectin-like proteins and ZP glycoproteins. We have previously reported the participation of binding sites for N-acetylglucosamine (GlcNAc) residues in human sperm function, including sperm interaction with the ZP. Additionally, previous results from our laboratory suggested that some of these events may be mediated by the glycosidase N-acetylglucosaminidase (beta-hexosaminidase, Hex, in mammals). In this study, we report the possible participation of Hex in human sperm-ZP interaction. Human recombinant Hex (hrHex) was obtained by expression in a stable transfected CHO cell line. When the recombinant enzyme was present during hemizona (HZ) assays, the number of sperm bound per HZ was significantly reduced. The same result was obtained when HZ were preincubated with hrHex. Additionally, the presence of a Hex-specific substrate during the HZ assay produced the same inhibitory effect. These results suggest the participation of a sperm Hex in the interaction with human ZP in vitro.
Mol Hum Reprod 2000 Aug
PMID:Evidence for the participation of beta-hexosaminidase in human sperm-zona pellucida interaction in vitro. 1090 79

The variability of serum and plasma levels of eosinophil granule proteins in different clinical conditions, interpreted as the result of different patterns of cytokine priming, suggests a selective mobilization of granule proteins. Inasmuch as piecemeal degranulation (PM) is the mechanism proposed for the differential release of eosinophil granule proteins, we decided to investigate whether blood eosinophils from allergic subjects show characteristics of PM during natural allergen challenge. Eosinophils from three birch-sensitive subjects were studied before and during the pollen season. Electron microscopy analysis showed that during the season, eosinophils presented morphologic features of PM. By immunogold labeling, eosinophil cationic protein (ECP) was detected not only in normal specific granules but also in the cytoplasm, in the vicinity of partially lucent specific granules. These results were confirmed by subcellular fractionation, where the amount of ECP associated with compartments containing small vesicles increased 2-fold during the pollen season. A study of the distribution of ECP, eosinophil peroxidase, and hexosaminidase in eosinophils of different densities showed that the profile of each of these proteins differed depending on cell density. All of these proteins decreased in the specific granule of hypodense cells and increased in other cell compartments. We conclude that allergen exposure causes PM of the peripheral blood eosinophils of allergic subjects, and that the density of these cells reflects the degree of degranulation. Our results provide novel information for the understanding of the selective mobilization of granule proteins into the circulation.
Am J Respir Cell Mol Biol 2000 Oct
PMID:Piecemeal degranulation of peripheral blood eosinophils: a study of allergic subjects during and out of the pollen season. 1101 18

GM2 activator protein (GM2-AP) belongs to a small group of non- enzymatic lysosomal proteins that act as cofactors in the sequential degradation of gangliosides. It has been postulated that GM2-AP extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-d-galactosamine and conversion to GM3. The high affinity of GM2-AP for GM2 is based on specfic recognition of the oligosaccharide moiety as well as the ceramide lipid tail. Genetic defects in GM2-AP result in an atypical form of Tay-Sachs disease known as variant AB GM2 gangliosidosis. The 2.0 A resolution crystal structure of GM2-AP reported here reveals a previously unobserved fold whose main feature is an eight-stranded cup-shaped anti-parallel beta-pleated sheet. The striking feature of the GM2-AP structure is that it possesses an accessible central hydrophobic cavity rather than a buried hydrophobic core. The dimensions of this cavity (12 Ax14 Ax22 A) are suitable for binding 18-carbon lipid acyl chains. Flexible surface loops and a short alpha-helix decorate the mouth of the beta-cup and may control lipid entry to the cavity.
J Mol Biol 2000 Dec 01
PMID:Crystal structure of human GM2-activator protein with a novel beta-cup topology. 1109 Feb 83

The goal of this study was to assess the contributions of the most important acid glycosidases to the processes connected with testes involution (in the summer) and spermatogenesis during the reproductive season (the spring) in ganders. Statistically significant increases in the specific activity of N-acetyl-beta-D-hexosaminidase, alpha-D-galactosidase, beta-D-galactosidase, and alpha-L-fucosidase during the period of testes involution were detected. Alpha-D-galactosidase, beta-D-galactosidase, and alpha-D-glucosidase showed an increase in the relative contribution of those multiple forms which are characterized by less acidic values of the pI during the reproductive season. It is suggested that the observed increases in the specific activity of beta-HEX, alpha-GAL, beta-GAL and alpha-FUC may be connected with the catabolism of glycoconjugates, when the spermatogenic activity of the testes declines. The increases in the relative contribution of less acidic forms of alpha-GAL, beta-GAL, and alpha-GLU during the reproductive season may be linked to the rise in the number of spermatocytes, spermatids and spermatozoa during spermatogenesis.
Comp Biochem Physiol B Biochem Mol Biol 2000 Nov
PMID:Sesonal changes in acid glycosidases from gander testes. 1112 69

We have previously demonstrated a marked change in sugar moieties of glycoproteins of the cuticle of the blue crab, Callinectes sapidus, between 0.5 and 3 h post-ecdysis. The present study has identified a glycosidase that appears in the cuticle during the early post-ecdysial hours. The enzyme has affinities for p-nitrophenyl derivatives of both N-acetylglucosamine and N-acetylgalactosamine. Both activities are competitively inhibited by chitobiose, suggesting that the enzyme could be a N-acetylhexosaminidase (EC 3.2.1.52). Atypical of N-acetylhexosaminidases described to date, this enzyme has a pH optimum of 7.0. The enzyme activity is high during the post-ecdysial period coincident with the changes in glycoprotein profiles observed in vivo. Partial purification of the enzyme has been accomplished by Sephacryl size-exclusion chromatography followed by concanavalin A affinity chromatography.
Comp Biochem Physiol B Biochem Mol Biol 2001 Apr
PMID:Glycosidase activity in the post-ecdysial cuticle of the blue crab, Callinectes sapidus. 1129 Apr 50

A cuticular glycosidase with characteristics of N-acetyl-beta-D-hexosaminidase (HexNAcase) was identified in post-ecdysial crab cuticle. Its appearance coincided with changes in cuticular glycoproteins and the onset of mineralization. To test if HexNAcase might be the causative agent in the alteration of the glycans and initiation of calcification, newly molted crab cuticle was treated with exogenous HexNAcase. Treating cuticular extracts from crabs at 0 h post-ecdysis with exogenous HexNAcase mimicked those changes observed in vivo. Specifically, the enzyme decreased the concanavalin A affinity of an 83-kDa glycoprotein that binds to calcite crystals in vitro. Treating pieces of 0 h post-ecdysial cuticle with HexNAcase rendered them capable of nucleating calcite in vitro (similar to 5 h post-ecdysial cuticle), while untreated, 0 h controls remained uncalcified. The data imply a role of the cuticular HexNAcase-like enzyme in the initiation of calcite nucleation in the newly formed exoskeleton.
Comp Biochem Physiol B Biochem Mol Biol 2001 Apr
PMID:Effects of exogenous N-acetylhexosaminidase on the structure and mineralization of the post-ecdysial exoskeleton of the blue crab, Callinectes sapidus. 1129 Apr 51

The plasma membrane of the spermatozoa of Drosophila melanogaster contains two integral proteins with glycosidase activity, beta-N-acetylglucosaminidase and alpha-D-mannosidase. Biochemical analysis and ultrastructural cytochemistry of spermatozoa of the autosomal male sterile mutant casanova reveal that at least one of these enzymes, beta-N-acetylglucosaminidase, is crucial for sperm-egg interactions. casanova sperm are motile, morphologically normal, are transferred to the female at mating, but are unable to fertilize the eggs. The mutation was localised by deficiency mapping to the chromosomal region 95E8-F7. Fluorimetric assays showed that the mutant's sperm have the same level of alpha-D-mannosidase activity as wild-type sperm, whereas beta-N-acetylglucosaminidase activity reaches only 51% of the wild-type level. The biochemical characteristics of alpha-D-mannosidase and of the residual beta-N-acetylglucosaminidase are the same as in wild-type males. Ultrastructural localization of the enzymes indicated that casanova spermatozoa lacks beta-N-acetylglucosaminidase on the plasma membrane covering the acrosome, whereas the location of this glycosidase at the terminal part of the sperm tail is indistinguishable from the wild-type situation. The results strongly suggest that in Drosophila the beta-N-acetylglucosaminidase of the plasma membrane covering the acrosome functions as a receptor for the glycoconjugates on the egg surface. We named the putative egg receptor EROS. This is the first evidence for an egg/sperm recognition system in insects. The mechanism is similar to those known from higher animals.
Mol Reprod Dev 2001 Oct
PMID:Male sterile mutant casanova gives clues to mechanisms of sperm-egg interactions in Drosophila melanogaster. 1155 26

During fasting of animals, there is decreased content of skin glycosaminoglycans (GAGs) accompanied by decrease in their biosynthesis. Since tissue GAG content depends on both synthesis and degradation of these molecules, we asked whether fasting affects the activity of several tissue glycosidases. Therefore we measured the activity of skin neutral and acidic endoglycosidases, some exoglycosidases: beta-N-acetylhexosaminidase [EC 3.2.1.30], beta-galactosidase [EC 2.1.23], beta-glucuronidase [EC 3.2.1.31], alpha-iduronidase [EC 3.2.1.76], and two sulfatases: arylsulfatase B [EC 3.1.6.1] and 6-sulfatase [EC 3.1.6.14] in the skin of control and fasted rats. Although fasting was accompanied by distinct decrease in the activity of most neutral endoglycosidases, no characteristic changes in the activity of exoglycosidases were found. In contrast, we found that fasting is associated with increase in the activity of acidic endoglycosidases (of lysosomal origin) which degraded hyaluronic acid, chondroitin-4-sulfate, chondroitin-6-sulfate and heparin. The same GAGs were decreased in the skin of fasted rats. Our data suggest that the phenomenon is a result of increased intracellular degradation of these molecules. Therefore, not only decreased biosynthesis of GAGs during fasting, but also increased their intracellular degradation may contribute to decrease in GAG skin content.
Comp Biochem Physiol B Biochem Mol Biol 2002 Mar
PMID:Glycosaminoglycan-degrading enzymes in the skin of fasted rats. 1195 38

Tay-Sachs and Sandhoff diseases are lysosomal storage disorders characterized by the absence of beta-hexosaminidase activity and the accumulation of GM2 ganglioside in neurons. In each disorder, a virtually identical course of neurodegeneration begins in infancy and leads to demise generally by 4-6 years of age. Through serial analysis of gene expression (SAGE), we determined gene expression profiles in cerebral cortex from a Tay-Sachs patient, a Sandhoff disease patient and a pediatric control. Examination of genes that showed altered expression in both patients revealed molecular details of the pathophysiology of the disorders relating to neuronal dysfunction and loss. A large fraction of the elevated genes in the patients could be attributed to activated macrophages/microglia and astrocytes, and included class II histocompatability antigens, the pro-inflammatory cytokine osteopontin, complement components, proteinases and inhibitors, galectins, osteonectin/SPARC, and prostaglandin D2 synthase. The results are consistent with a model of neurodegeneration that includes inflammation as a factor leading to the precipitous loss of neurons in individuals with these disorders.
Hum Mol Genet 2002 May 15
PMID:Molecular pathophysiology in Tay-Sachs and Sandhoff diseases as revealed by gene expression profiling. 1201 16

To better understand the molecular regulation of defense responses in members of the genus Pinus, we tested the expression of various chitinase homologs in response to pathogen-associated signals. PSCHI4, a putative extracellular class II chitinase, was secreted into liquid medium by pine cells and was also secreted by transgenic tobacco cells that ectopically expressed pschi4. Extracellular proteins of pine were separated by isoelectric focusing; PSCHI4 was not associated with fractions containing detectable beta-N-acetylglucosaminidase or lysozyme activities. However, other fractions contained enzyme activities that increased markedly after elicitor treatment. The pschi4 transcript and protein accumulated in pine seedlings challenged with the necrotrophic pathogen Fusarium subglutinans f. sp. pini, with the protein reaching detectable levels in susceptible seedlings concomitant with the onset of visible disease symptoms. Additional chitinase transcripts, assigned to classes I and IV based on primary sequence analysis, were also induced by pathogen challenge. Jasmonic acid induced class I and class IV but not class II chitinase, whereas salicylic acid induced all three classes of chitinase. These results show that multiple chitinase homologs are induced after challenge by a necrotrophic pathogen and by potential signaling molecules identified in angiosperms. This suggests the potential importance of de novo pathogenesis-related (PR) gene expression in pathogen defense responses of pine trees.
Mol Plant Microbe Interact 2002 Apr
PMID:Pathogen challenge, salicylic acid, and jasmonic acid regulate expression of chitinase gene homologs in pine. 1202 77


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