Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclic AMP in Strongylocentrotus purpuratus sperm was elevated approximately 2-fold by theophylline or 1-methyl-3-isobutylxanthine. Factors released from sea urchin eggs (FRE) elevated sperm cyclic AMP by about 7-fold within 1 min, and the combination of FRE with theophylline increased sperm cyclic AMP up to 100-fold within 1 min. Cyclic GMP in sea urchin sperm was slightly elevated by theophylline, but was lowered by FRE. Cyclic GMP in sperm treated with FRE plus theophylline was not higher than in sperm treated with theophylline alone. The ability of FRE-containing sea water to increase sperm cyclic AMP in the presence of theophylline was altered only slightly if at all by boiling, but it was decreased by about 50% by dialysis and destroyed by ashing. Filtration of FRE on Sephadex G-50 columns yielded two peaks of cyclic AMP-elevating activity. One peak (peak I) was eluted at the column void volume, and the other (peak II) was retained by the column. The cyclic GMP-lowering activity was located in fractions approximately corresponding to peak I of cyclic AMP-elevating activity. Dialysis of FRE-containing sea water before its application to the G-50 column virtually eliminated peak II of the cyclic AMP-elevating activity. When the cyclic AMP-elevating activity in peak I was filtered on Bio Gel A-5m columns, it also migrated at or near the column void volume. Fractions corresponding to peak I contained material that inhibited both guanylate and adenylate cyclase activities in broken cell preparations of sperm and guanylate cyclase from rat lung. The inhibitory material was stable to boiling, non-dialyzable, and destroyed by ashing. Under a variety of conditions, FRE-containing sea water or cyclic AMP-elevating peaks I or II did not stimulate sperm adenylate cyclase activity in broken cell preparations.
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PMID:Effects of egg factors on cyclic nucleotide metabolism in sea urchin sperm. 0 75

The flagellar creatine kinase (TCK) of Strongylocentrotus purpuratus sperm is both a principal component of sperm tail membrane preparations and a cytosolic enzyme. An improved purification scheme identified three pools of TCK, termed TCK I, TCK II, and TCK III. TCK I and II were essentially homogeneous protein preparations, while TCK III was heavily contaminated with other flagellar proteins, predominantly guanylate cyclase, and alpha- and beta-tubulin. The three TCK species are roughly present in a 1:10:1 ratio as assessed by activity measurements. TCK I and II are similar proteins as shown by two-dimensional gel electrophoresis, partial proteolytic fragmentation, and cellulose polyacetate electrophoresis and have the same pH-dependent specific activity. However, they are functionally distinct with respect to their capacity to associate with lipids. TCK II associated readily with phospholipid liposomes and detergent micelles, while TCK I did not. Association of TCK II was as a protein monomer with an apparent Kd of approximately 1-2 mM at a 10(4):1 lipid or detergent to protein ratio. Whereas the Kd estimates were pH independent, the rate of association increased 2-3-fold between pH 6.5 and 8. The data are consistent with membrane-association of TCK II being a two-step process, involving a pH-dependent, intramolecular, TCK-specific step and a charge-facilitated, but pH-independent, membrane association step. Membrane association of TCK may, together with microtubule association (Tombes, R.M., Farr, A., and Shapiro, B.M. (1988) Exp. Cell Res. 178, 307-317) represent a mechanism required for specific accumulation of the enzyme within the flagellum.
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PMID:Membrane association of flagellar creatine kinase in the sperm phosphocreatine shuttle. 168 Aug 67

A cDNA clone for the membrane form of guanylate cyclase has been isolated from the testis of the sea urchin Strongylocentrotus purpuratus. An open reading frame predicts a protein of 1125 amino acids including an apparent signal peptide of 21 residues; a single transmembrane domain of 25 amino acids divided the mature protein into an amino-terminal, extracellular domain of 485 amino acids and a carboxyl domain of 594 intracellular amino acids. Three potential Asn-linked glycosylation sites were present in the proposed extracellular domain. The deduced protein sequence was homologous to the protein kinase family and contained limited but significant regions of identity with a low molecular weight atrial natriuretic peptide receptor. The carboxyl region (202 amino acids) was 42% identical with a subunit of the cytoplasmic form of guanylate cyclase recently cloned from bovine lung (Koesling, D., Herz, J., Gausepohl, H., Niroomand, F., Hinsch, K.-D., Mulsch, A., Bohme, E., Schultz, G., and Frank, R. (1988) FEBS Lett. 239, 29-34). Therefore, the membrane form of guanylate cyclase is a member of an apparently large family of proteins that includes the low molecular weight atrial natriuretic peptide receptor, the soluble form of guanylate cyclase and protein kinases.
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PMID:The membrane form of guanylate cyclase. Homology with a subunit of the cytoplasmic form of the enzyme. 256 49

Speract (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly), a peptide obtained from the culture medium of Strongylocentrotus purpuratus eggs, stimulates the respiration and motility of S. purpuratus spermatozoa under appropriate conditions. Resact (Cys-Val-Thr-Gly-Ala-Pro-Gly-Cys-Val-Gly-Gly-Gly-Arg-LeuNH2), a peptide obtained from Arbacia punctulata eggs also stimulates the metabolism and motility of A. punctulata spermatozoa, however, it fails to stimulate S. purpuratus spermatozoa. Early biochemical responses of the spermatozoa to the egg peptides include a net H+ efflux and elevations of cyclic AMP and cyclic GMP concentrations. In addition, in A. punctulata spermatozoa, a major plasma membrane protein is modified in response to resact such that its apparent molecular weight shifts from 160,000 to 150,000. If cells are incubated with 32P, the 160,000 molecular weight form of the protein becomes radiolabeled; subsequent addition of resact causes a rapid loss of 32P from the protein. The plasma membrane protein appears to be the enzyme, guanylate cyclase; coincident with the shift in apparent molecular weight, enzyme activity decreases by as much as 90%. Since speract fails to cause these responses in A. punctulata, it can be concluded that the events are receptor-mediated.
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PMID:Peptides associated with eggs: mechanisms of interaction with spermatozoa. 288 30

A peptide (resact) associated with the eggs of the sea urchin, Arbacia punctulata, which stimulates sperm respiration rates by 5-10-fold, was purified and its amino acid sequence was determined. The sequence was found to be Cys-Val-Thr-Gly-Ala-Pro-Gly-Cys-Val-Gly-Gly-Gly-Arg-Leu-NH2. The peptide was subsequently synthesized by solid phase methods, amidated at the carboxyl-terminal Leu, and shown to be identical to the isolated, native material. The peptide half-maximally stimulated A. punctulata spermatozoan respiration at 0.5 nM and half-maximally elevated cyclic GMP concentrations at 25 nM at an extracellular pH of 6.6. The increase in oxygen consumption was coupled with a stimulation of motility. However, at elevated extracellular pH (pH 8.0), resact failed to appreciably stimulate respiration while the elevations of cyclic GMP continued to occur. Resact did not cross-react with sperm cells obtained from Lytechinus pictus or Strongylocentrotus purpuratus; a peptide (speract) obtained from S. purpuratus eggs (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) which activates S. purpuratus sperm respiration did not stimulate A. punctulata spermatozoa. Resact caused a shift in the apparent molecular weight (160,000-150,000) of a major sperm plasma membrane protein; as with cyclic GMP elevations, this response was evident at extracellular pH values of both 6.6 and 8.0. The protein exists in the cell as a phosphoprotein and 32P is released coincident with the molecular weight change. Approximately 115 nM resact caused one-half-maximal conversion of the 160,000-dalton protein after 1 min of incubation. Resact caused the apparent molecular weight conversion of the protein within 5 s and appeared to do so in an irreversible manner. The molecular weight change of the protein was also observed after the addition of monensin A (25 microM) and NH4Cl (40 mM), two agents known to elevate intracellular pH and to increase sperm respiration rates. The membrane protein appears to be the enzyme guanylate cyclase, but since concentrations of resact causing one-half-maximal conversion of the Mr = 160,000 form of the enzyme are about 250 times higher than those causing one-half-maximal stimulation of respiration, the relationship of the apparent molecular weight conversion to a subsequent physiological event remains unclear.
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PMID:A peptide associated with eggs causes a mobility shift in a major plasma membrane protein of spermatozoa. 615 45

Speract, a decapeptide from Strongylocentrotus purpuratus sea urchin eggs, transiently stimulates a membrane guanylyl cyclase and activates a K(+)-selective channel that hyperpolarizes sperm. However, previous studies of sperm and of sperm membrane vesicles reached conflicting conclusions about the mechanisms that open these channels. We find that speract hyperpolarizes and increases the cGMP content of flagellar vesicles. We confirm previous findings that intravesicular GTPgammaS and GTP enhance this hyperpolarization, but not GDPbetaS. The G protein activators AlF(-)(4) and mastoparan also are ineffective. Thus, it is unlikely that a G protein participates in the speract response. In contrast, hyperpolarization responses to speract are increased by 3-isobutyl-1-methylxanthine, which preferentially inhibits cGMP-selective phosphodiesterases of sperm, and the 8Br-cGMP derivative hyperpolarizes vesicles in the absence of speract. The responses to speract and to 8Br-cGMP have similar ionic selectivities (K(+) > Rb(+) > > Li(+) > Na(+)) and sensitivities to the channel blockers 4-aminopiridine and 3, 4-dichlorobenzamil, indicating that they likely result from opening of the same K(+) channel. Inhibitors that preferentially inhibit cAMP-selective phosphodiesterases do not alter responses to speract, and permeant cAMP analogs do not hyperpolarize vesicles. In addition, inhibitors of protein kinases and phosphatases fail to alter vesicle hyperpolarization by speract. The increase in vesicular cGMP content produced by speract therefore may directly mediate opening of the channel that hyperpolarizes sperm membrane vesicles. Similar mechanisms presumably operate in intact sperm.
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PMID:Participation of a K(+) channel modulated directly by cGMP in the speract-induced signaling cascade of strongylocentrotus purpuratus sea urchin sperm. 1079 Mar 26

Chemotaxis of sperm is an important step toward fertilization. During chemotaxis, sperm change their swimming behavior in a gradient of the chemoattractant that is released by the eggs, and finally sperm accumulate near the eggs. A well established model to study chemotaxis is the sea urchin Arbacia punctulata. Resact, the chemoattractant of Arbacia, is a peptide that binds to a receptor guanylyl cyclase. The signaling pathway underlying chemotaxis is still poorly understood. Stimulation of sperm with resact induces a variety of cellular events, including a rise in intracellular pH (pHi) and an influx of Ca2+; the Ca2+ entry is essential for the chemotactic behavior. Previous studies proposed that the influx of Ca2+ is initiated by the rise in pHi. According to this proposal, a cGMP-induced hyperpolarization activates a voltage-dependent Na+/H+ exchanger that expels H+ from the cell. Because some aspects of the proposed signaling pathway are inconsistent with recent results (Kaupp, U.B., J. Solzin, J.E. Brown, A. Helbig, V. Hagen, M. Beyermann, E. Hildebrand, and I. Weyand. 2003. Nat. Cell Biol. 5:109-117), we reexamined the role of protons in chemotaxis of sperm using kinetic measurements of the changes in pHi and intracellular Ca2+ concentration. We show that for physiological concentrations of resact (<25 pM), the influx of Ca2+ precedes the rise in pHi. Moreover, buffering of pHi completely abolishes the resact-induced pHi signal, but leaves the Ca2+ signal and the chemotactic motor response unaffected. We conclude that an elevation of pHi is required neither to open Ca(2+)-permeable channels nor to control the chemotactic behavior. Intracellular release of cGMP from a caged compound does not cause an increase in pHi, indicating that the rise in pHi is induced by cellular events unrelated to cGMP itself, but probably triggered by the consumption and subsequent replenishment of GTP. These results show that the resact-induced rise in pHi is not an obligatory step in sperm chemotactic signaling. A rise in pHi is also not required for peptide-induced Ca2+ entry into sperm of the sea urchin Strongylocentrotus purpuratus. Speract, a peptide of S. purpuratus may act as a chemoattractant as well or may serve functions other than chemotaxis.
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PMID:Revisiting the role of H+ in chemotactic signaling of sperm. 1527 71

Apoptosis is proposed to be a major cause of death in shrimp viral infections. From our previous study, an apoptosis-related gene, Pm-Alix, was identified from the black tiger shrimp. Its expression was high in defence-related tissues including haemocytes and the lymphoid organ. To clarify its possible role in shrimp, we used Pm-Alix as bait in a yeast two-hybrid analysis to search for Alix interacting proteins in shrimp. Two cDNA sequences discovered had homology to a predicted ubiquitin C of the purple sea urchin, Strongylocentrotus purpuratus, and to a guanylyl cyclase of the red swamp crayfish, Procambarus clarkii. In vitro pull-down assays confirmed positive interaction between Pm-Alix and both proteins. Tissue distribution analysis revealed that Pm-Alix and the two binding partners were widely expressed in various tissues but more highly expressed in haemocytes. However, no significant positive or negative correlation was found in the expression of these genes as shrimp approached morbidity and death after challenge with white spot syndrome virus. Thus, the results suggested that Alix and its interacting partners did not play a direct role related to shrimp death.
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PMID:Identification and characterization of Alix/AIP1 interacting proteins from the black tiger shrimp, Penaeus monodon. 2041 59

Speract, a decapeptide from Strongylocentrotus purpuratus sea urchin eggs, transiently stimulates a membrane guanylyl cyclase and activates a K(+)-selective channel that hyperpolarizes the sperm. Membrane potential recordings with fluorescent dyes in sperm flagellar vesicles were used to determine if calmodulin participates in the signal transduction induced by speract. The vesicle hyperpolarization induced by speract was inhibited by the calmodulin antagonists: trifluoperazine, mastoparan; N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide, (W-7); and N-(6-Aminohexyl)-1-naphthalenesulfonamide, (W-5). Since that inhibition occurred at concentrations at which calmodulin action is inhibited by these compounds, the overall findings suggested that calmodulin could be involved in the speract response. The speract response was Ca(2+)-independent however. Ten millimolar EGTA does not inhibit the hyperpolarization and 2 mM BAPTA only partially inhibited the response. High concentrations of calmodulin-dependent kinase II and phosphatase inhibitors did not alter the response of the flagella vesicles to speract. Taken as a whole, these results indicate that the speract-induced hyperpolarization involves the participation of calmodulin in a Ca2+ independent manner.
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PMID:Calmodulin antagonists inhibit sea urchin sperm hyperpolarization necessary for directed movement toward the egg. 2242 88