Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possibility that the surface of the egg of the sea urchin Arbacia punctulata contains a species-specific receptor for sperm has been investigated. The extent of fertilization of eggs of A. punctulata, which is proportional to the number of sperm, is unaffected by the presence of either eggs or membranes prepared from eggs of Strongylocentrotus purpuratus. In marked contrast, membranes prepared from eggs of A. punctulata quantitatively inhibit fertilization of A. punctulata eggs by A. punctulata sperm. Several lines of evidence indicate that this inhibition is due to the presence of a membrane-associated glycoprotein that binds to the sperm, thus preventing them from interacting with receptor on the surface of the eggs. First, eggs treated with trypsin are incapable of being fertilized, although they can be activated with the Ca2+ ionophore A23187. Moreover, membranes prepared from eggs pretreated with trypsin do not inhibit fertilization of eggs. Second, receptor isolated in soluble form from surface membranes binds to sperm and thus prevents them from fertilizing eggs; the inhibition by soluble receptor is species-specific. Third, the soluble receptor binds to concanavalin A-Sepharose. Fourth, eggs are incapable of being fertilized if they are pretreated with concanavalin A. The specificity of inhibition, and the affect of trypsin and concanavalin A on intact eggs, suggest that the receptor is a species-specific macromolecule located on the surface of the eggs. The sensitivity of the receptor to trypsin, and its ability to bind to concanavalin A, indicate that it is a glycoprotein.
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PMID:Identification of a sperm receptor on the surface of the eggs of the sea urchin Arbacia punctulata. 55 17

Changes in the topography of the sea urchin egg after fertilization were studied by scanning and transmission electron microscopy. Strongylocentrotus purpuratus eggs were treated with dithiothreitol to modify the vitelline layer and to prevent formation of a fertilization membrane. Dithiothreitol treatment caused the microvilli to become more irregular in shape, length, and diameter than those of untreated eggs. The microvilli were similarly modified by trypsin treatment. This effect did not appear to be due to disruption of cytoskeletal elements beneath the plasma membrane, for neither colchicine nor cytochalasin B altered microvillar morphology. Thus, it appears that the vitelline layer may act in the maintenance of surface form of unfertilized eggs. Since dithiothreitol-treated eggs did not elevate a fertilization membrane, scanning electron microscopy could be used to directly observe modifications in the egg plasma membrane after fertilization. The wave of cortical granule exocytosis initiated at the point of attachment of the fertilizing sperm was characterized by the appearance of pits that subsequently opened, releasing the cortical granule contents and leaving depressions upon the egg surface. The perigranular membranes inserted during exocytosis were seen as smooth patches between the microvillous patches remaining from the original egg surface. This produced a mosaic surface with more than double the amount of membrane of unfertilized eggs. The mosaic surface subsequently reorganized to accommodate the inserted membrane material by elongation of microvilli. Blebs and membranous whorls present before reorganization suggested the existence of an unstable intermediate state of plasma membrane reorganization. Exocytosis and mosaic membrane formation were not blocked by colchicine or cytochalasin B, but microvillar elongation was blocked by cytochalasin B treatment.
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PMID:Changes in the topography of the sea urchin egg after fertilization. 98 32

The sea urchin blastula secretes a hatching enzyme (HE) that dissolves the fertilization envelope. HE was collected from the supernatant seawater of cultures of hatched Strongylocentrotus purpuratus blastulae, and concentrated 20 times by ultrafiltration. The proteolytic activity of HE using casein as substrate was inhibited by the chymotrypsin inhibitors, chymostatin and N-tosyl-L-phenylalanine chloromethyl ketone. The activity was not inhibited by inhibitors (antipain, elastatinal, pepstatin, phosphoramidon, soybean trypsin inhibitor, and N alpha-p-tosyl-L-lysine chloromethyl ketone) of other types of proteases. HE did not hydrolyze the synthetic trypsin substrate, alpha-N-benzoyl-L-arginine ethyl ester, but did hydrolyze the synthetic substrate of chymotrypsin, N-benzoyl-L-tyrosine ethyl ester (BTEE). The BTEEase activity of HE was completely inhibited by the chymotrypsin inhibitors chymostatin and 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC). Chymostatin inhibited the natural hatching of sea urchin blastulae. Application of HE to freshly fertilized sea urchin eggs, 2 h after insemination, caused premature dispersal of the hardened fertilization envelope. Chymostatin and NCDC inhibited HE-induced lysis of the fertilization envelope, while inhibitors of other types of proteases were ineffective. These data suggest that sea urchin HE is a chymotrypsin-like protease we call "chymotrypsin."
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PMID:Evidence that hatching enzyme of the sea urchin Strongylocentrotus purpuratus is a chymotrypsin-like protease. 307 14

Incubation in trypsin effects a phenotypic switch from short to long cilia (greater than 30 micron) in hatched blastulae of the sea urchin, Arbacia punctulata. To determine how trypsin causes such a switch we tested whether the phenomenon was unique to the species, Arbacia, and to the protease, trypsin. With two other echinoderm species, the sand dollar, Dendraster excentricus, and the sea urchin, Strongylocentrotus purpuratus, trypsin incubation increased the percentage of long cilia. During incubation of D. excentricus in trypsin, the percentage of long cilia increased progressively from the normal 10% long cilia of the apical tuft to 45-50% long cilia covering 1/2-3/4 of the embryo. With S. purpuratus blastulae, however, the percentage of long cilia was lower (32-40%) and the results were more variable. Of the additional proteases tested with D. excentricus, elastase was more effective than trypsin in terms of the percentage of long cilia (58%), the mean length, and the broad distribution of lengths formed. Thermolysin was about as effective as trypsin but chymotrypsin was much less so. Thus, increases in ciliary length were not unique to a particular echinoderm species or to incubation in trypsin. The magnitude of the change in length distribution, however, was species- and enzyme-dependent. An extracellular or membrane component with differential susceptibility to various proteases may, therefore, be involved in altering ciliary length.
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PMID:Phenotypic switching to long cilia effected by various proteases: results with Dendraster excentricus and Stronglyocentrotus purpuratus blastulae. 364 79

In earlier studies from our laboratory, the intact sperm receptor was partially purified from Strongylocentrotus purpuratus crude egg membranes, but due to its insolubility, it was not possible to purify it to homogeneity. Nonetheless, this receptor preparation bound with species specificity to acrosome-reacted sperm, thereby inhibiting fertilization. Antibodies against the partially pure receptor inhibited fertilization in S. purpuratus (but not Arbacia punctulata) by coating the egg surface, indicating the presence of binding sites that can be species-specifically recognized by both sperm and antibody molecules. Recently we were able to further purify and characterize the receptor from S. purpuratus eggs. Chaotropic agent solubilization of the receptor prepared from crude egg membranes yielded a very high molecular weight glycoconjugate that had many of the properties of a proteoglycan. The receptor interacted with binding in an in vitro assay and bound with species specificity to acrosome-reacted sperm to inhibit fertilization. Unfortunately, this receptor preparation was soluble only in certain chaotropic agents. Exhaustive Pronase digestion of the intact receptor yielded a soluble high-molecular-weight (greater than 10(6)) polysaccharide that was virtually devoid of protein. This glycosaminoglycan-like fragment was highly sulfated, and contained fucose, galactosamine, and iduronic acid. The fragment inhibited fertilization, but did not do so with species specificity. Recently, soluble molecules with receptor activity were generated by treating intact dejellied eggs with trypsin. These proteolytically derived molecules contained (on a weight basis) approximately equal amounts of protein and carbohydrate. Importantly, they inhibited fertilization with species specificity. The results suggested that the binding activity was conferred by the polysaccharide component of the receptor and that the intact receptor and the tryptic fragments contained structural elements in the polypeptide chain necessary for species recognition.
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PMID:Characterization of the Strongylocentrotus purpuratus egg cell surface receptor for sperm. 382 83

The Ca2+-stimulated release of cortical vesicle (cortical granule) contents from the cell surface complex (CSC) of the sea urchin egg is an in vitro model for exocytosis. To gain insight into the molecular mechanism of exocytosis we investigated the sensitivity of this model to sulfhydryl modification and proteolytic digestion. Our findings include the following: (a) Proteolytic treatment with trypsin or pronase of CSC prepared from the eggs of Strongylocentrotus purpuratus increased the free Ca2+ concentration required to elicit exocytosis. Although a small increase in the Ca2+ threshold was detected after mild proteolysis, high concentrations of trypsin (0.5 mg/ml) and prolonged incubation (3 h) were required to render the CSC unresponsive to high concentrations of Ca2+ (0.5 mM). Despite the severity of the proteolytic digestions required to inactivate the CSC, the individual cortical vesicles remained intact, as gauged by the latency of ovoperoxidase, a cortical vesicle enzyme. (b) As previously shown (Haggerty, J. C., and R. C. Jackson, 1983, J. Biol. Chem. 258:1819-1825), cortical exocytosis can be blocked by sulfhydryl-modifying reagents such as N-ethylmaleimide (NEM). In this report we demonstrate that NEM inhibits by increasing the Ca2+ threshold required for exocytosis. When CSC that had been completely inactivated by NEM modification was briefly digested, on ice, with a low concentration of trypsin (or several other proteases), exocytotic activity was restored. Although the Ca2+ threshold of the reactivated CSC was slightly higher than that of untreated CSC, it was nearly identical to that of control CSC, which was trypsinized but not treated with NEM. We discuss the significance of these results with regard to the molecular mechanism of exocytosis.
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PMID:Mild proteolytic digestion restores exocytotic activity to N-ethylmaleimide-inactivated cell surface complex from sea urchin eggs. 400 35

A low-molecular-mass zinc-binding protein was purified from the eggs of the sea urchin Paracentrotus lividus using procedures that included gel-permeation and anion-exchange chromatography followed by HPLC. The primary structure of this protein was derived from the sequences of peptide fragments obtained by digestion with trypsin and thermolysin. The reconstructed sequence showed the presence of 20 cysteinyl residues, thus resembling that of a metallothionein. The Paracentrotus protein was most similar to the metallothionein of Strongylocentrotus purpuratus, another member of the order of Echinoida, living along the coast of the Pacific Ocean. However, the presence of non-conservative amino acid substitution, together with a deletion of two residues in the Strongylocentrotus metallothionein, make the similarity scores of the two sea urchin proteins lower than that of metallothioneins from vertebrates of the same order. In addition, the present data show that sea urchin metallothioneins display no homology with metallothioneins of any other species.
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PMID:Isolation and primary structure determination of a metallothionein from Paracentrotus lividus (Echinodermata, Echinoidea). 759 93

The sea urchin sperm cell is an advantageous model for studying ligand-mediated exocytosis. Sperm can be obtained in vast quantities and induced to undergo exocytosis of the acrosomal vesicle with great synchrony. During sea urchin fertilization, egg jelly (EJ) triggers the sperm acrosome reaction (AR) which is required for sperm binding and fusion with the egg. Uncertainty exists as to the exact biochemical nature of the AR inducer. The following study was performed in an attempt to clarify the nature of the inducer. EJ from individual females (Strongylocentrotus purpuratus) was analyzed on SDS-PAGE gels. Each female had a unique composition of EJ macromolecules, but all females possessed the previously described fucose sulfate polymer (FSP). Two electrophoretic isotypes of FSP were discovered; 87% of females had only one isotype and 13% had both. Both FSP isotypes bound to the REJ protein (receptor for egg jelly) purified from sperm. The two FSP isotypes had almost equal potency in inducing the AR. EJ was fractionated by DEAE chromatography in 6 M urea/4% beta-mercaptoethanol. All AR-inducing activity coeluted with FSP. FSP, purified by trypsin digestion followed by dialysis, was twice as active as the non-trypsin-digested control at inducing the AR. EJ was digested with proteinase K, boiled in detergent and beta-mercaptoethanol, and subjected to sucrose density gradient sedimentation. The FSP and AR activity had superimposable sedimentation patterns. Purified FSP had no associated peptide component. Sperm from individual males differed in the concentration dependency of purified FSP to induce the AR. The data indicate that the 138/82 kDa EJ glycoproteins, previously thought to act as AR inducers, do not appear to be involved in triggering the AR. The data are consistent with the hypothesis that FSP is the only inducer of the AR of this sea urchin species.
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PMID:The fucose sulfate polymer of egg jelly binds to sperm REJ and is the inducer of the sea urchin sperm acrosome reaction. 940 2

Trypsin-like activity is secreted from eggs of many species at fertilization, and this activity is believed to be critical for the block to polyspermy. Here we show that a cortical granule serine protease of sea urchins is the major and perhaps only protease family member important for fertilization. Zymography assays suggest that the cortical granules contain a single serine protease that can undergo autocatalysis and is secreted upon egg activation. We used this finding to identify a cDNA clone from a Strongylocentrotus purpuratus ovary cDNA library that encodes a 581-amino-acid-residue protein that we refer to as cortical granule serine protease 1 (CGSP1). The catalytic domain of the protein contains the essential residues of the catalytic triad characteristic of a member of the trypsin-like family of serine proteases and the N-terminus of CGSP1 resembles the ligand-binding domain of the low-density lipoprotein (LDL) receptor. Antibodies raised separately to both the protease and LDL receptor-like domains each localize to the cortical granules of unfertilized eggs. Furthermore, the full-length form of CGSP1, as well as intermediate and active forms of the protease, is detected in cortical granules by immunoblot analysis. Our evidence suggests that CGSP1 is activated at fertilization and is responsible for the protease-mediated reactions that follow cortical granule exocytosis and contribute to the block to polyspermy.
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PMID:The cortical granule serine protease CGSP1 of the sea urchin, Strongylocentrotus purpuratus, is autocatalytic and contains a low-density lipoprotein receptor-like domain. 1037

Interest in chordate evolution has emphasized a need for a better understanding of the comparative neuroanatomy of invertebrate deuterostomes. However, molecular and genetic approaches to neurobiological studies in these groups are hampered by a lack of neuron-specific molecular markers. A monoclonal antibody, 1E11, is neuron specific and is useful in identification of neural structures in larvae and adults of echinoderms, hemichordates, and urochordates. To identify a neuron-specific gene product, we have characterized the antigen recognized by 1E11. In immunoblots and immunoprecipitations of neural tissue from adult Strongylocentrotus purpuratus, 1E11 recognizes a 57-kDa band. Tandem mass spectrometry of trypsin digests of the 57-kDa band permitted peptide mass mapping and sequencing of five peptides. All of the sequenced peptides, and 12 additional mass-mapped peptides, are found within the open reading frame of a cDNA encoding synaptotagmin B (Sp-SynB). In situ RNA hybridizations with synaptotagmin B probes with S. purpuratus larvae reveal a pattern of expression that is similar to that revealed by the antibody 1E11. Antibodies produced against a bacterially expressed Sp-SynB protein recognize a 57-kDa protein and colocalize with 1E11. When a full-length Sp-SynB cDNA is expressed in chicken embryonic cells, the cells become immunoreactive to 1E11. We conclude that synaptotagmin B is a gene expressed in neurons that has conserved epitopes in other invertebrate deuterostomes.
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PMID:Neuron-specific expression of a synaptotagmin gene in the sea urchin Strongylocentrotus purpuratus. 1653 80


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