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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The isolated nuclei of wheat embryo possess the ATPase activity. The addition of Mg2+ and Ca2+ significantly increases the activities of nuclear ATPases, whereas Hg2+, Cu2+ and Mn2+ inhibit the activity. The activating effect of Mg2+ is enhanced by an addition of Na and K ions. The activity of wheat embryo nuclear Mg-ATPase is higher than its Ca-ATPase activity; both ATPases also differ in their pH optima. Separation of total nuclear protein according to the solubility of its individual protein components in wheat and strong salt solutions, using the detergents, as well as ammonium sulfate precipitation and dialysis do not result in separation of Mg-activated and Ca-activated ATPases, although their levels of activities and ratios change in the course of fractionation. The Mg- and Ca-ATPase activities of the wheat embryo nuclei were found in the nuclear fraction of albumin, in nonhistone proteins and nuclear membranes. In the albumin nuclear fraction and subfractions of non-histone proteins the higher level of activity is observed in Ca-ATPase, whereas in the nuclei and soluble fractions of residual proteins in Mg-ATPase.
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PMID:[Properties and localization of Mg- and Ca-ATpase activities in wheat embryo cell nuclei]. 14 25

A nuclear protein(s) from rat or pig stomach recognized a conserved sequence in the 5'-upstream regions of the rat and human H+/K(+)-ATPase alpha subunit genes. A gel retardation assay suggested that part of the binding site was located in the TAATCAGCTG sequence. No nuclear proteins capable of the binding could be detected in other tissues of rat (liver, brain, kidney, spleen and lung) or pig liver. The sequence motif (GATAGC) located 5'-upstream of the beta-subunit gene also seemed to be recognized by the same protein, because the binding of nuclear protein to the sequence motifs in the alpha and beta subunits was mutually competitive. Considering the sense-strand sequence of the binding motif in the alpha-subunit gene, we conclude that (G/C)PuPu(G/C)NGAT(A/T)PuPy is a core sequence motif for the gastric specific DNA binding protein (PCSF, parietal cell specific factor).
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PMID:Sequence motif in control regions of the H+/K+ ATPase alpha and beta subunit genes recognized by gastric specific nuclear protein(s). 131 19

We have isolated mutants of the yeast Saccharomyces cerevisiae that are defective in localization of nuclear proteins. Chimeric proteins containing the nuclear localization sequence from SV40 large T-antigen fused to the N-terminus of the mitochondrial F1 beta-ATPase are localized to the nucleus. Npl (nuclear protein localization) mutants were isolated by their ability to grow on glycerol as a consequence of no longer exclusively targeting SV40-F1 beta-ATPase to the nucleus. All mutants with defects in localization of nucleolar proteins and histones are temperature sensitive for growth at 36 degrees C. Seven alleles of NPL3 and single alleles of several additional genes were isolated. NPL3 mutants were studied in detail. NPL3 encodes a nuclear protein with an RNA recognition motif and similarities to a family of proteins involved in RNA metabolism. Our genetic analysis indicates that NPL3 is essential for normal cell growth; cells lacking NPL3 are temperature sensitive for growth but do not exhibit a defect in localization of nuclear proteins. Taken together, these results indicate that the mutant forms of Npl3 protein isolated by this procedure are interfering with nuclear protein uptake in a general manner.
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PMID:A mutant nuclear protein with similarity to RNA binding proteins interferes with nuclear import in yeast. 139 78

The rat gastric H+/K(+)-ATPase beta subunit gene was cloned, and its nucleotide sequence was determined. The coding region is separated by 6 introns, whereas the related human Na+/K(+)-ATPase beta subunit gene was shown to have 5 introns (Lane, L.K., Shull, M.M., Whitmer, K.R., and Lingrel, J.B. (1989) Genomics 5, 445-453). The positions of introns 1, 2, and 5 of the two genes were the same. The similarities in intron/exon organizations and primary structures (30-40% identical residues) suggest that the beta subunit genes for H+/K(+)-ATPases were derived from a common ancestor. The upstream region of the rat H+/K(+)-ATPase beta subunit gene contains direct repeat sequences and palindromes, potential binding sites for RNA polymerase II and E4TF1, and CACCC box sequences. Gel retardation assay demonstrated that the stomach, but not other tissues (liver, brain, kidney, spleen, and lung), has a nuclear protein(s) capable of binding to the regions upstream of the potential RNA polymerase II binding sites (TATA box). The nuclear protein(s) are suggested to recognize three tandem GATAGC sequences and may be important for controlled transcription of the H+/K(+)-ATPase beta subunit gene in gastric parietal cells.
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PMID:The rat H+/K(+)-ATPase beta subunit gene and recognition of its control region by gastric DNA binding protein. 165 72

We have previously demonstrated [Rihs, H.-P. and Peters, R. (1989) EMBO J., 8, 1479-1484] that the nuclear transport of recombinant proteins in which short fragments of the SV40 T-antigen are fused to the amino terminus of Escherichia coli beta-galactosidase is dependent on both the nuclear localization sequence (NLS, T-antigen residues 126-132) and a phosphorylation-site-containing sequence (T-antigen residues 111-125). While the NLS determines the specificity, the rate of transport is controlled by the phosphorylation-site-containing sequence. The present study furthers this observation and examines the role of the various phosphorylation sites. Purified, fluorescently labeled recombinant proteins were injected into the cytoplasm of Vero or hepatoma (HTC) cells and the kinetics of nuclear transport measured by laser microfluorimetry. By replacing serine and threonine residues known to be phosphorylated in vivo, we identified the casein kinase II (CK-II) site S111/S112 to be the determining factor in the enhancement of the transport. Either of the residues 111 or 112 was sufficient to elicit the maximum transport enhancement. The other phosphorylation sites (S120, S123, T124) had no influence on the transport rate. Examination of the literature suggested that many proteins harboring a nuclear localization sequence also contain putative CK-II sites at a distance of approximately 10-30 amino acid residues from the NLS. CK-II has been previously implicated in the transmission of growth signals to the nucleus. Our results suggest that CK-II may exert this role by controlling the rate of nuclear protein transport.
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PMID:The rate of nuclear cytoplasmic protein transport is determined by the casein kinase II site flanking the nuclear localization sequence of the SV40 T-antigen. 184 77

Human cells contain a nuclear protein interacting with Alu repeats, and this protein seems to recognize a conserved sequence motif, GGAGGC, present within the RNA polymerase III promoter and within the SV40 T-antigen-dependent ARS-like element. To study the potential functional role of this element, we have inserted the sequence into a chloramphenicolacetyltransferase (CAT) expression vector with a SV40 promoter and enhancer element from the up-stream region of the human c-myc gene, and transfected HeLa cells with the resulting plasmid. Analysis of expression by the CAT assay indicates that the Alu-derived sequence supresses transcription of the CAT gene driven by the c-myc enhancer/SV40 promoter. The Alu-derived sequence also inhibits ARS activity of the c-myc enhancer. The data allow the explanation of the transcriptional inactivity of Alu repeats in HeLa cells, and suggest the existence of a negative control of Alu transcription.
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PMID:Transcription and replication silencer element is present within conserved region of human Alu repeats interacting with nuclear protein. 215 7

A number of closely related post-transcriptional facets of RNA metabolism show nuclear compartmentation, including capping, methylation, splicing reactions, and packaging in ribonucleoprotein particles (RNP). These nuclear 'processing' events are followed by the translocation of the finished product across the nuclear envelope. Due to the inherent complexity of these interrelated events, in vitro systems have been designed to examine the processes separately, particularly so with regard to translocation. A few studies have utilized nuclear transplantation/microinjection techniques and specialized systems to show that RNA transport occurs as a regulated phenomenon. While isolated nuclei swell in aqueous media and dramatic loss of nuclear protein is associated with this swelling, loss of RNA is not substantial, and most studies on RNA translocation have employed isolated nuclei. The quantity of RNA transported from isolated nuclei is related to hydrolysis of high-energy phosphate bonds in nucleotide additives. The RNA is released predominantly in RNP: messenger-like RNA is released in RNP which have buoyant density and polypeptide composition similar to cytoplasmic messenger RNP, but which have distinctly different composition from those in heterogeneous nuclear RNP. Mature 18 and 28S ribosomal RNA is released in 40 and 60S RNP which represent mature ribosomal subunits. RNA transport proceeds with characteristics of an energy-requiring process, and proceeds independently of the presence or state of fluidity of nuclear membranes. The energy for transport appears to be utilized by a nucleoside triphosphatase (NTPase) which is distributed mainly within heterochromatin at the peripheral lamina. Photoaffinity labeling has identified the pertinent NTPase as a 46 kD polypeptide which is associated with nuclear envelope and matrix preparations. The NTPase does not appear to be modulated via direct phosphorylation or to reflect kinase-phosphatase activities. A large number of additives (including RNA and insulin) produce parallel effects upon RNA transport and nuclear envelope NTPase, strengthening the correlative relationship between these activities. Of particular interest has been the finding that carcinogens induce specific, long-lasting increases in nuclear envelope (and matrix) NTPase; this derangement may underlie the alterations in RNA transport associated with cancer and carcinogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Nucleocytoplasmic RNA transport. 241 44

The assembly of ribosomes in bacterial cells is a complex process that remains poorly characterized. The in vitro assembly of active ribosomal subunits from purified RNA and protein components indicates that all of the information for proper assembly resides in the primary sequences of these macromolecules. On the other hand, the in vitro requirement of unphysiological heating steps suggests that this pathway may not accurately reflect the in vivo pathway, and that other proteins may be required. One approach to identify any additional proteins is to isolate second-site revertants of mutants defective in ribosome assembly. Ribosomal protein L24 is essential in the assembly of 50S subunits. We have identified an Escherichia coli gene, srmB, that, when expressed at high copy number, can suppress the effect of a temperature-sensitive lethal mutation in L24. The SrmB amino-acid sequence has sequence identity with mouse translation initiation factor eIF-4A and with the human nuclear protein, p68. The purified SrmB protein is a nucleic acid-dependent ATPase, like eIF-4A, but can also bind RNA in the absence of ATP and other auxiliary protein factors. The RNA dependent ATPase activity of SrmB suggests that like, eIF-4A, it could be involved in specific alterations of RNA secondary structure.
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PMID:An eIF-4A-like protein is a suppressor of an Escherichia coli mutant defective in 50S ribosomal subunit assembly. 246 20

Human retrotransposons, Alu-family DNA repeats (AFRs), have variable nucleotide sequence but conservative short elements, which may have important functions, are also present. In our previous reports we have described human nuclear DNA-binding protein interacting with AFRs and evidence was presented that the protein recognizes sequence motif 5'-GGAGGC-3' which is conserved in the spacer of RNA polymerase III promoter of AFRs and in the SV40 T-antigen-dependent replication origin of AFRs. In this study it was found that double-stranded synthetic oligonucleotides containing indicated conservative sequences of AFRs actually have high-affinity binding site for HeLa nuclear protein. The data suggest that non-infected human cells contain nuclear DNA-binding protein which recognizes the conservative sequence motif of AFRs - GGAGGC.
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PMID:Human nuclear protein interacting with a conservative sequence motif of Alu-family DNA repeats. 254 28

In this paper, progress towards the goal of understanding communication between the nucleus and cytoplasm using an in vitro system is reviewed. To probe the mechanism of nuclear targeting, we developed an in vitro transport system and have begun to dissect the highly selective process of nuclear transport. The basic parameters of transport were defined using an easily isolated nuclear protein, nucleoplasmin. To study the interaction of nuclear targeting signals with the pore, an artificial nuclear transport substrate was constructed, which consists of human serum albumin coupled to the signal sequence of the SV40 T-antigen. A similar peptide-protein conjugate was made using a mutant signal sequence. These conjugates were fluorescently labeled and/or tagged with gold and tested for transport in the in vitro system. High levels of nuclear transport of the wild-type signal sequence-containing protein were observed, while no transport of the mutant signal sequence-containing protein was seen. Thus, the in vitro system correctly recognizes the single amino acid change between the wild-type and mutant signal sequences. We found that the observed nuclear transport was completely dependent on the presence of ATP. Using the in vitro system we identified a specific inhibitor of nuclear transport, the lectin wheat germ agglutinin (WGA), which we find binds directly to the nuclear pore. Probing blots of nuclear proteins with 125I-WGA identified a family of nuclear pore glycoproteins, including one major glycoprotein of 62K (K = 10(3)Mr) molecular weight. With the inhibitor and the in vitro assay, it has been possible to experimentally separate nuclear transport into two steps: (1) a step in which the signal sequence-bearing protein binds to the pore, followed by (2) a step in which the protein translocates through the pore. It is this second step which is the ATP-dependent step of transport, since pore binding but not translocation was seen to occur in the absence of ATP.
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PMID:Nuclear transport in vitro. 261 52


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