Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Verapamil, a potent calcium channel blocker, was administered orally at three different doses to guinea pigs for both short- (4 weeks) and long-term (12 weeks) effects. The drug treatment stimulated Ca(++)-transport and Ca(++)-activated ATPase in isolated plasma membrane vesicles of guinea pig spermatozoa. Ca(++)-uptake studies exhibited partial to complete restoration of stimulated Ca(++)-transport during recovery period, whereas the CA(++)-activated ATPase system remained stimulated even after 4 and 6 weeks of withdrawal of the drug treatment. The lack of inhibitory effect of verapamil on Ca(++)-uptake ruled out the involvement of calcium channels in spermatozoal calcium uptake in guinea pigs. The stimulatory effect of the drug on CA(++)-uptake, on the other hand, might indicate the possible capability of this lipophilic compound to induce favourable changes in the lipid microenvironment of the membrane, wherein the integral membrane proteins operate.
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PMID:Verapamil stimulates Ca(++)-uptake and Ca(++)-ATPase in plasma membrane vesicles of guinea pig spermatozoa. 213 44

Digitonin-permeabilized guinea pig spermatozoa undergo acrosomal matrix dispersion in response to 2.0 mM CaCl2. In this report, the effects of pH and metal ions on matrix dispersion in permeabilized spermatozoa are examined. Calcium-induced dispersion of the acrosomal matrix was dependent on the calcium concentration; the response was not observed at concentrations of CaCl2 less than 50 microM. Magnesium could not substitute for calcium and, in fact, had a retarding effect on the calcium-induced response. Matrix dispersion was also found to be pH-dependent. The induction of matrix dispersion was inhibited at pH 5.6 and pH 9.5 relative to the responses observed at pH 6.3 and pH 7.8. Nigericin induced acrosomal matrix dispersion in the absence of added calcium, indicating a possible role of Na+/H+ exchange across the outer acrosomal membrane in initiating the matrix modification. Sodium was required for the action of nigericin; the ionophore was ineffective in medium in which choline chloride or sucrose was substituted for NaCl. In contrast, the calcium-induced dispersion of the acrosomal matrix occurred in the absence of sodium. Furthermore, low concentrations of calcium inhibited an adenosine triphosphatase activity associated with isolated acrosomal apical segments. These data are consistent with the hypothesis that calcium induces alkalinization of the acrosome, leading to matrix dispersion. However, permeabilized spermatozoa incubated at either pH 9.5 or in the presence of 50 mM NH4Cl at pH 7.5 failed to undergo spontaneous matrix dispersion, suggesting that elevated intraacrosomal pH alone was not sufficient to initiate the reaction. The proposed alternative hypothesis is that calcium initiates matrix dispersion by a mechanism in which elevated intraacrosomal pH may be a secondary response.
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PMID:Regulation of acrosomal matrix dispersion in digitonin-permeabilized guinea pig spermatozoa. 214 57

We have discovered a ring-shaped particle of 12.5 nm diameter, 14.5S and apparent molecular weight of approximately 570,000 that displays 6-fold radial symmetry and is composed of a single kind of an acidic (pI approximately 5.5) polypeptide of Mr 97,000 (p97). Using antibodies to this protein we have detected its occurrence in a wide range of cells and tissues of diverse species from frog to man, including highly specialized cells such as mammalian erythrocytes and spermatozoa. In Xenopus laevis oocytes, the particle is found in both isolated nuclei and in manually enucleated ooplasms, which corresponds to immunofluorescence staining dispersed over both nucleoplasm and cytoplasm. The particle has a N-ethylmaleimide (NEM)-inhibitable Mg2(+)-ATPase activity, and its amino acid sequence, as deduced from cDNA clones, displays considerable homology to the mammalian NEM-sensitive fusion protein (NSF) and yeast Sec18p believed to be essential for vesicle fusion in secretory processes, indicating that these three proteins belong to the same multigene family.
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PMID:An abundant and ubiquitous homo-oligomeric ring-shaped ATPase particle related to the putative vesicle fusion proteins Sec18p and NSF. 214 Jul 70

The idea of a PCr-circuit is supported by the fact that in fully differentiated and highly specialized cells with high sudden energy turnover, e.g., skeletal and cardiac muscle [Wallimann and Eppenberger, 1985], brain and retina photoreceptor cells [Wallimann et al, 1986a], spermatozoa [Tombes and Shapiro, 1985; Wallimann et al, 1986b] and Torpedo electrocytes [Wallimann et al, 1985] mitochondrial CK is generally found in conjunction with cytosolic CK's with a significant fraction of the latter being associated subcellularly in a compartmented fashion at intracellular sites of high energy turnover. It is also becoming apparent that some of the cytosolic CK is specifically associated with membranes possibly via membrane anchors, e.g., with the SR-membrane where CK was shown to be functional by supporting a significant portion of the maximal Ca2(+)-pumping rate [Rossi et al, 1988; submitted]. Similar membrane associations of CK have been shown with the post-synaptic acetylcholine-receptor-rich membrane, the invaginated, and non-innervated face membrane of electrocytes, rich in Na+/K+ ATPase as well as with synaptic vesicles [Wallimann et al, 1985], with the sperm-tail plasma membrane [Wallimann et al, 1986a], and recently also with rod outer segment plasma membranes of bovine photoreceptor cells [Quest et al, 1987; Hemmer et al, 1989]. Thus, for all the above cells the PCr-circuit seems to represent an efficient, flexible, and highly responsive accessory, crucial not only as an energy back-up system, but also as a regulator of energy flux (channeling) and as a fine-tuning device of local ATP-levels. The strength of such a regulated channeling circuit operating at relatively low adenine nucleotide levels compared to the high total PCr and Cr pools, which are metabolically inert, is its high sensitivity towards ADP [Wallimann et al, 1984] that is preventing in excitable cells the accumulation of ADP and AMP unless severe stress, such as hypoxia or ischaemia is imposed. Additional details concerning the PCr-circuit model in muscle and our current ideas about the structure-function relationships of mitochondrial have been described elsewhere [Wallimann and Eppenberger, 1985; Schlegel et al, 1988; Schnyder et al, 1988].(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The subcellular compartmentation of creatine kinase isozymes as a precondition for a proposed phosphoryl-creatine circuit. 220 65

Turnover rates of oxidative energy metabolism were measured as oxygen consumption in untreated and caffeine-stimulated epididymal bull spermatozoa respiring with lactate. Incubation of spermatozoa with 1 mM caffeine led to an increase in respiration of approx. 60%. The rate of uncoupled respiration and the vanadate-insensitive part of oxygen consumption were not affected by caffeine. The small effect of ouabain on respiration (-10%) indicated a minor contribution of Na+/K+-ATPase to the ATP consumption. The major part of ATP turnover was caused by motility shown by the strong linear correlation between respiration and motility in untreated and caffeine-treated spermatozoa. In comparison with ejaculated spermatozoa investigated in a previous study, epididymal cells exhibited the same rates of uncoupled and ouabain-sensitive respiration. The efficiency of transforming mitochondrially-produced ATP into cell motion was the same in epididymal and ejaculated spermatozoa. The ATP-producing capacity of sperm mitochondria was utilized in untreated epididymal, in caffeine-stimulated epididymal and in ejaculated spermatozoa, by 20-25%, 40-45% and 45-50%, respectively. The results showed that the capacity of mitochondrial. ATP formation remains unchanged after ejaculation and is utilized to a higher extent by stimulated motility. Treatment with caffeine affected epididymal spermatozoa in a similar manner.
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PMID:Quantification of aerobic energy turnover in epididymal bull spermatozoa. 229 10

The acrosome reaction was induced in nearly 100% of mouse spermatozoa with dibutyryl cyclic guanosine monophosphate (dbcGMP) before ouabain treatment. Acrosome-reacted spermatozoa could not penetrate the zona pellucida, but readily fertilized zona-free eggs. Exposure to ouabain at concentrations as low as 10(-7) M had a noticeable inhibitory effect upon fertilization. Similar results were obtained with a second ATPase inhibitor, digoxin. These results show that ion-pump inhibitors block the union of gametes which are otherwise fully competent to fertilize. These findings suggest that a membrane potential maintained by ion pumps is a necessary prerequisite for gamete fusion.
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PMID:Ion pump ATPase inhibitors block the fertilization of zona-free mouse oocytes by acrosome-reacted spermatozoa. 243 4

Unknown factors in the seminal plasma of normal semen that affect the motility of spermatozoa have a positive effect on adenosine triphosphatase (ATPase) enzyme activity. In an attempt to produce such an effect, spermine, spermidine and kallikrein were added to the incubation media in which spermatozoal ATPase enzyme activity was determined. These seminal substances increased the triple ATPase enzyme activity of spermatozoa from oligoasthenozoospermic men. We propose that the ATPase enzyme activity of spermatozoa may indicate sperm motility as a biochemical test.
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PMID:The effect of spermine, spermidine and kallikrein on the triple adenosine triphosphatase enzyme activity of spermatozoa in males with oligoasthenozoospermia. 252 16

A calmodulin-like protein (CLP) has been identified in buffalo (Bubalus bubalis) seminal plasma and partially characterized. It was heat stable and had properties similar to those of the calcium-binding protein, calmodulin. It is present in relatively high concentrations in buffalo seminal plasma. When added to buffalo red-blood cell plasma membrane (RBC ghosts) it increased Ca++, Mg++-ATPase activity by 112%. The activation is counteracted by chlorpromazine and trifluoperazine, the anti-calmodulin drugs. A similar calmodulin-activated Ca++ pump has been found predominantly in the tail fractions of buffalo spermatozoa. The existence of CLP in buffalo seminal plasma may be responsible for some of the physiological changes observed during capacitation and acrosome reaction. A hypothesis has been proposed involving CLP in regulation of these events.
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PMID:Calmodulin-like protein in buffalo (Bubalus bubalis) seminal plasma and its effect on sperm Ca++, Mg++-ATPase. 252 48

Two different affinity-purified polyclonal antibodies were prepared against A polypeptides of dynein 1 extracted from sea urchin sperm. These antibodies, named AD1 and AD2, reacted exclusively with the alpha and beta heavy chains of dynein 1. Using these antibodies, we analyzed their cross-reactivity with dynein of mammalian cells. Immunohistochemically, both AD1 and AD2 stained dynein-related structures such as cilia of rabbit tracheal epithelia and flagella of rat spermatozoa. Immunoblots of the proteins extracted from mammalian cilia and flagella revealed the presence of A polypeptide-like proteins which cross-reacted with AD1 and AD2. Immunoblot analysis showed that the cross-reactive proteins were localized to the 370-kDa band of rabbit cilia and the 390- and 350-kDa bands of rat sperms. The reaction patterns showed that there were some differences between the two antibodies. On ciliary protein immunoblots, AD1 recognized about half of the broad band region which reacted with AD2, and AD1 also recognized only the 350-kDa band of the flagella extract, suggesting that the antibody reveals only a beta-like polypeptide. Immunoprecipitation studies using the ciliary proteins and AD2 confirmed that the immunoreactive protein had ATPase activity. Given these results, we have characterized mammalian dyneins previously reported by other laboratories.
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PMID:Analysis of mammalian dynein using antibodies against A polypeptides of sea urchin sperm flagellar dynein. 253 Jan 2

In an in vitro investigation, methylmercury (MeHg) reduced the motility of rat spermatozoa probably by the inhibition of succinate dehydrogenase and ATPase activities. Concomitant morphological changes observed in the spermatozoa were coiled tails and kinks in midpiece and tail regions.
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PMID:Toxic effects of methylmercury on spermatozoa in vitro. 253 Jan 5


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