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 present investigation probes the intranuclear molecular changes that serve to link the nuclear binding of estradiol with the hormone-stimulated ribonucleoprotein (RNP) transport in the rat uterus. Within 2 min of in vitro exposure of isolated uterine nuclei to 10 nM 17 beta-estradiol a Mg2+-dependent nuclear ATPase becomes activated and reaches its peak activity. This is immediately followed by a phase of ATP resynthesis. This newly synthesized ATP serves as the substrate for the nuclear protein kinases. Cyclic AMP inhibits this ATP resynthesis and, as a consequence, prevents the estradiol-stimulated nuclear protein kinase activity and the exit of the RNP-estradiol complex from the nuclei. cGMP is stimulatory to the estradiol-mediated nuclear ribonucleoprotein transport.
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PMID:Estradiol-stimulated nuclear ribonucleoprotein transport in the rat uterus: a molecular basis. 316 27

Correct targeting of nuclear proteins is mediated by nuclear localization sequences (NLS) which permit specific binding to the nucleus and subsequent translocation across the nuclear envelope via the nuclear pore complex. It is proposed that nuclear import is facilitated by NLS-receptors which reside in the cytoplasm and at the nuclear pore. These NLS-receptors could facilitate an early step of nuclear protein import, i.e. targeting and binding of nuclear proteins at the nuclear pore. We have generated anti-idiotype antibodies against the SV40 T-antigen nuclear localization sequence that allowed us to study NLS-binding proteins in a variety of different organisms. Proteins of similar size are recognized by these antibodies in yeast, Drosophila, rat and human cells. Cytological analysis indicates that the NLS-binding proteins reside in part at nuclear pores. One of the proteins recognized by anti-idiotype antibodies is identical to a previously identified NLS-binding protein. Using isolated yeast nuclei we demonstrate that the anti-idiotype antibodies compete for binding of nuclear proteins in vitro. We show that the yeast mutant npl3, which is defective in nuclear protein localization, has an altered distribution of antigens recognized by these anti-idiotype antibodies, at the semi-permissive temperature. Our results suggest that a set of proteins common to various eukaryotes recognizes nuclear localization sequences.
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PMID:Analysis of conserved binding proteins for nuclear localization sequences. 768 Jun 61

We have isolated a human cDNA clone encoding HIP116, a protein that binds to the SPH repeats of the SV40 enhancer and to the TATA/inhibitor region of the human immunodeficiency virus (HIV)-1 promoter. The predicted HIP116 protein is related to the yeast SNF2/SWI2 transcription factor and to other members of this extended family and contains seven domains similar to those found in the vaccinia NTP1 ATPase. Interestingly, HIP116 also contains a C3HC4 zinc-binding motif (RING finger) interspersed between the ATPase motifs in an arrangement similar to that found in the yeast RAD5 and RAD16 proteins. The HIP116 amino terminus is unique among the members of this family, and houses a specific DNA-binding domain. Antiserum raised against HIP116 recognizes a 116-kDa nuclear protein in Western blots and specifically supershifts SV40 and HIV-1 protein-DNA complexes in gel shift experiments. The binding site for HIP116 on the SV40 enhancer directly overlaps the site for TEF-1, and like TEF-1, binding of HIP116 to the SV40 enhancer is destroyed by mutations that inhibit SPH enhancer activity in vivo. Purified fractions of HIP116 display strong ATPase activity that is preferentially stimulated by SPH DNA and can be inhibited specifically by antibodies to HIP116. These findings suggest that HIP116 might affect transcription, directly or indirectly, by acting as a DNA binding site-specific ATPase.
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PMID:Cloning of an SNF2/SWI2-related protein that binds specifically to the SPH motifs of the SV40 enhancer and to the HIV-1 promoter. 787 28

To test the hypothesis that the enhancement of cell killing by post-irradiation treatment with caffeine (CAF) is mediated by alterations in chromatin structure, several nuclear parameters were examined in both caffeine-responsive and non-responsive cell lines. Cell killing, as determined by clonogenic assay, was not enhanced by post-irradiation treatment with 5 mM caffeine in a human diploid fibroblast line (AG1522) but an effect was seen in a SV40 T-antigen transformed derivative (1522-a). CAF caused a complete reversal of the radiation-induced G2 + S phase cell-cycle delays in the transformed cell line but only a partial reversal was noted for the parental cell line. The nuclear endpoints examined, which may be indicative of chromatin conformational changes, included enzymatic accessibility, DNA loop structure, and nuclear protein composition. In assays of the ability of DNA to undergo supercoiling changes, it was found that nucleoids isolated from CAF-treated cells had a significantly reduced propidium-iodide relaxable DNA loop size. The constraints to DNA unwinding produced by CAF were also maintained even in the presence of large numbers of single strand breaks produced by a test dose of radiation (10 Gy). This effect did not correlate well with the ability of CAF to enhance radiation-induced cell killing. The two other nuclear endpoints did detect differences between the normal and transformed cell lines. CAF had no effect on the DNase I digestion kinetics of the normal fibroblasts. However, in the transformed cell line, CAF appeared to render an additional 10-15% of the genome accessible to DNase I digestion. Several radiation and CAF-induced changes in the polypeptide pattern of isolated nucleoids were detected after metabolic labelling with 35S-methionine or 32P-orthophosphoric acid. While the identities of these proteins remain to be established, many had relative molecular weights similar to the other reported radiation-altered proteins and human cell cycle control gene products. The present cell lines should provide a convenient system in which to identify a nuclear protein change specifically associated with the ability of CAF to enhance radiation-induced cell killing.
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PMID:Differential post-irradiation caffeine response in normal diploid versus SV40-transformed human fibroblasts: potential role of nuclear organization and protein-composition. 810 71

Progress in molecular biological studies on the gastric proton pump (H+/K(+)-ATPase) now enable us to discuss not only its subunit protein structures and catalysis but also the organizations of its subunit genes and their cell-specific transcription. The primary structures of the catalytic alpha and glycosylated beta subunits are similar to those of the corresponding subunits of Na+/K(+)-ATPase. The residues located in the catalytic and cation binding sites have been proposed from the combined results of protein chemical studies and sequence comparisons of P-type cation transporting ATPases. Most of the positions of exon/intron boundaries of the genes for the H+/K(+)- and Na+/K(+)-ATPase alpha and beta subunits are conserved, suggesting that the alpha and beta subunit genes, respectively, of the two ATPases were derived from common ancestors. In contrast to the Na+/K(+)-ATPase subunits, the H+/K(+)-ATPase alpha and beta subunits are expressed specifically in gastric parietal cells. Consistent with their cell-specific transcription, a gastric mucosal nuclear protein(s) was shown to recognize a sequence motif in the 5'-upstream regions of the H+/K(+)-ATPase alpha and beta subunit genes. Furthermore, novel zinc finger proteins (GATA-GT1 and GATA-GT2) that bind to this motif were found in the gastric parietal cells. These proteins are likely to play important roles in transcriptional regulation of the gastric proton pump genes.
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PMID:Gastric proton pump (H+/K(+)-ATPase): structure and gene regulation through GATA DNA-binding protein(s). 818 38

Sequence-specific DNA binding activators of gene transcription may be assisted by SWI2 (SNF2), which contains a DNA-dependent ATPase domain. We have isolated a human complementary DNA encoding a 205K nuclear protein, BRG1, that contains extensive homology to SWI2 and Drosophila brahma. We report here that a SWI2/BRG1 chimera with the DNA-dependent ATPase domain replaced by corresponding human sequence restored normal mitotic growth and capacity for transcriptional activation to swi2- yeast cells. Point mutation of the conserved ATP binding site lysine abolished this complementation. This mutation in SWI2 exerted a dominant negative effect on transcription in yeast. A lysine to arginine substitution at the corresponding residue of BRG1 also generated a transcriptional dominant negative in human cells. BRG1 is exclusively nuclear and present in a high M(r) complex of about 2 x 10(6). These results show that the SWI2 family DNA-dependent ATPase domain has functional conservation between yeast and humans and suggest that a SWI/SNF protein complex is required for the activation of selective mammalian genes.
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PMID:BRG1 contains a conserved domain of the SWI2/SNF2 family necessary for normal mitotic growth and transcription. 823 56

The gastric proton pump (H+/K(+)-ATPase) is a typical P-type ATPase consisting of the alpha and beta subunits and secreting acid into stomach. This enzyme is similar to Na+/K(+)-ATPase in primary structure and gene organization. The exon/intron organizations of the genes for the two subunits of H+/K(+)-ATPase are highly similar to those of the corresponding subunits of Na+/K(+)-ATPase. In contrast to Na+/K(+)-ATPase subunits, alpha and beta subunits of H+/K(+)-ATPase are expressed specifically in gastric parietal cells. Consistently, a sequence motif [(G/C)PuPu(G/C)NGAT(A/T)PuPy] in the 5'upstream regions of the H+/K(+)-ATPase subunit genes was recognized by the gastric mucosal nuclear protein(s). We found that two novel zinc-finger proteins (GATA-GT1 and GATA-GT2) are present in the gastric parietal cells and bind to this motif. These proteins activate the transcription of the reporter gene connected with the 5'-upstream regions of the H+/K(+)-ATPase subunit genes. These results suggest that gastric GATA-DNA binding proteins have roles in activating transcription of H+/K(+)-ATPase genes in parietal cells.
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PMID:[Gastric proton pump: genes and their expression]. 892 Jun 87

We have observed that in NZBWF1 mice the affinity for L-tryptophan binding to hepatic nuclei in vitro is markedly less than that of Swiss mice. In vitro binding of [3H]tryptophan to hepatic nuclei from both strains was determined without and with unlabeled L-tryptophan (10(-4) mol/L). The relative specific binding of L-tryptophan to hepatic nuclei in vitro was 60.9 +/- 4.4% for Swiss mice and 35.8 +/- 5.4% (P < 0.01) in NZBWF1 mice. The total specific binding (bound radioactivity/mg nuclear protein) of L-tryptophan to hepatic nuclei in vitro was 74.9% (P < 0.05) lower in NZBWF1 mice than in Swiss mice. Other strains (DBA, SJL and BALB/c) had specific binding affinities similar to that of Swiss mice. Serum and hepatic free tryptophan concentrations and hepatic tryptophan dioxygenase activity in mice that were food-deprived overnight or 1 h after tube-feeding L-tryptophan (20 mg/100 g body weight) were similar in the strains of mice. In vitro [14C] leucine incorporation into protein using hepatic microsomes of mice 1 h after tube-feeding L-tryptophan (20 mg/100 g body weight) revealed a significantly greater (P < 0.05) increase relative to food-deprived controls in Swiss mice (76.8 +/- 19.2%) than the increase in NZBWF1 mice (26.5 +/- 2.6%). Nuclear [14C]-labeled RNA release in vitro was increased 77.2 +/- 18.0% by tube-feeding of L-tryptophan in Swiss but only 7.6 +/- 5.8% (P < 0.02) in NZBWF1 mice. Liver nuclear poly(A)-polymerase and nucleoside triphosphatase activities were variably increased by the administration of L-tryptophan in both strains. In summary, compared with Swiss mice, NZBWF1 mice have a lower specific binding affinity for L-tryptophan by hepatic nuclei, and this alteration may account for the other differences in responses to L-tryptophan by the two strains.
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PMID:Differences in tryptophan binding to hepatic nuclei of NZBWF1 and Swiss mice: insight into mechanism of tryptophan's effects. 903 27

Nuclear proteins are transported actively through nuclear pores by a selective, mediated process. The process is mediated by a nuclear localization signal (NLS), and can be divided into at least two steps, (a) targeting to the pores and (b) translocation through the pores. The first step involves the formation of a stable complex containing a nuclear protein, termed nuclear pore-targeting complex (PTAC), in the cytoplasm. The second step, translocation, requires at least two soluble factors, a small GTPase Ran and its interacting protein p10/nuclear transport factor 2 (NTF2), along with nuclear pore complex components. These findings have been generally obtained by using the NLS of SV40 large T-antigen, and data concerning the detailed mechanism are now accumulating. Transport pathways other than for the SV40 T-antigen, for example, extracellular signal-dependent nuclear protein import pathway, have also recently been studied. Considering all these observations, one should be able to attain an understanding of the mechanism of intracellular information transduction between cytoplasm and the nucleus.
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PMID:How proteins are transported from cytoplasm to the nucleus. 919 17

We produced and affinity-purified polyclonal antibodies to adrenal myosin I. These antibodies recognize adrenal myosin I by Western blot analysis (116 kDa) and inhibit the actin-activated ATPase activity of purified adrenal myosin I. They also recognize a 120-kDa protein in extracts prepared from many different cell lines. Fluorescence microscopy demonstrated the presence of immunoreactive material in the perinuclear region, the leading edges, and the nuclei of 3T3 cells. Fluorescence microscopy also demonstrated nuclear staining in mouse oocytes at the germinal vesicle stage and in the pronuclei during fertilization. Confocal and immunoelectron microscopy confirmed the intranuclear localization. Electron microscopy also demonstrated staining of structures in nucleoli that are thought to be associated with rDNA transcription. Western blot analyses revealed the presence of the 120-kDa protein in extracts prepared from nuclei that are apparently free of cytosolic contamination. The same nuclear protein binds 125I-calmodulin and is photoaffinity labeled with [alpha-32P]ATP. The 120-kDa protein was partially purified from twice washed nuclei using ammonium sulfate fractionation and gel filtration chromatography. Column fractions containing 120-kDa protein as revealed by Western blot analysis also contain K+-EDTA ATPase activity. The 120-kDa protein was also shown to bind actin in the absence, but not the presence, of ATP. Since K+-EDTA ATPase activity, actin, and ATP binding are defining features of the members of the myosin superfamily of proteins, we propose that the 120-kDa protein is a previously undescribed myosin I isoform that is an intranuclear actin-based molecular motor.
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PMID:Evidence for the presence of myosin I in the nucleus. 920 39


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