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)

We have developed an experimental system to study nucleocytoplasmic traffic of proteins in living mammalian cells. Toward this goal, substrates were generated that contain several copies of Aequorea victoria green fluorescent protein (GFP). To follow facilitated transport across the nuclear envelope we created reporter proteins that carry different nuclear localization sequences (NLSs). The expression of reporter genes was controlled by an inducible promoter. Transiently transfected HeLa cells were employed to follow the sorting of fluorescent reporter proteins. When NLS-GFP fusions were located in HeLa cells, we found that direct fusion of the NLS derived from SV40 T-antigen to GFP prevented nuclear accumulation of the protein. However, insertion between NLS and GFP of different linkers encoding small amino acid residues produced reporter proteins that were competent for nuclear import. Taken together, we have generated unique tools for the characterization of nuclear protein import in dividing mammalian cells.
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PMID:In vivo analysis of nuclear protein traffic in mammalian cells. 934 16

We have isolated cDNAs encoding a novel member of the DEAD box RNA helicase family from Arabidopsis. The protein, named AtDRH1, is composed of 619 amino acids and the central portion has high similarity with the helicase core region of a prototypic RNA helicase, the human nuclear protein p68. The N- and C-terminal regions are considerably diverged from the animal and yeast p68 homologs at the amino acid sequence level, but like the p68 subfamily members, an RGG box-like domain is present near the C-terminus. RNA blot analysis showed that the AtDRH1 transcript accumulates at a high level and almost equally in every part of the Arabidopsis plant. The purified, recombinant AtDRH1 was capable of unwinding double-stranded RNA in the presence of ATP or dATP and of hydrolyzing ATP. The ATPase activity was stimulated by some single-stranded RNAs and DNAs, including poly(A) and poly(dT), but not by poly(dA). The ability of the polynucleotides to stimulate the ATPase activity was largely consistent with their affinity for AtDRH1. These results show that AtDRH1 is a novel type of ATP/dATP-dependent RNA helicase and polynucleotide-dependent ATPase.
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PMID:Characterization of a DEAD box ATPase/RNA helicase protein of Arabidopsis thaliana. 959 48

We have isolated a novel nuclear protein with a molecular mass of 49 kDa (TIP49a) from rat liver. The rat TIP49a showed structural resemblance to several bacterial RuvBs and also displayed Walker A and B motifs. We overproduced the recombinant TIP49a in Escherichia coli and purified it to near homogeneity. Biochemical investigations demonstrated that TIP49a possessed ATPase activity that was stimulated by single-stranded DNA but neither by double-stranded DNA nor by any forms of RNA polymers tested. Moreover, a UV cross-linking assay indicated TIP49a specifically interacted with ATP. Interestingly, we found that DNA duplex was unwound by the recombinant TIP49a in the presence of ATP or dATP. Optimal concentrations of ATP and Mg2+ for the helicase activity were 1-2 mM and 0.25-1 mM, respectively. Displacement of the DNA strand occurred in the 3' to 5' direction with respect to the single-stranded DNA flanking the duplex. Western blot analysis revealed that TIP49a was abundantly expressed in testes and moderately in spleen, thymus, and lung. In mouse seminiferous tubules, the protein was restrictively observed in germ lineages from late pachytene spermatocytes to round spermatids. From these observations, we propose that TIP49a is a novel DNA helicase and may play a role in nuclear processes such as recombination and transcription.
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PMID:A rat RuvB-like protein, TIP49a, is a germ cell-enriched novel DNA helicase. 1033 18

TIP49a (just called as simply TIP49 in previous reports [Kanemaki et al., 1997; Makino et al., 1998]) was found in a rat nuclear protein complex that included the TATA-binding protein. TIP49a possesses multiple sequence motifs for ATPase and DNA helicase. Since TIP49a structurally resembles prokaryotic DNA helicase RuvB, TIP49a is resumed to be a putative DNA helicase. We demonstrated TIP49a-related gene(s) in variety organisms from human to archaea. Amino acid identities expressed as aligned scores of human, yeast, and A. fulgidus TIP49a gene counterparts to the rat sequence were 99, 67, and 46, respectively. Strikingly, two homologous regions of mammalian TIP49a and bacterial RuvB exhibited an aligned score of 17-38. We demonstrated that the eukaryotic TIP49a counterparts were immunologically conserved. These lines of evidence show that the TIP49a gene is a notable example of a highly conserved gene among organisms. An extensive homology search revealed another class of TIP49-related gene in the eukaryotes, designated as TIP49b. Moreover, a phylogenetical study suggested that archaeal TIP49 genes belong to the TIP49b ancestor but not to the TIP49a one and that TIP49a evolved from TIP49b in accordance with divergence of archaea and eukarya. The TIP49 gene family is thought to play a fundamental role in a biological activity.
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PMID:A notable example of an evolutionary conserved gene: studies on a putative DNA helicase TIP49. 1056 43

Autosomal dominant hereditary spastic paraplegia (AD-HSP) is a genetically heterogeneous neurodegenerative disorder characterized by progressive spasticity of the lower limbs. Among the four loci causing AD-HSP identified so far, the SPG4 locus at chromosome 2p2-1p22 has been shown to account for 40-50% of all AD-HSP families. Using a positional cloning strategy based on obtaining sequence of the entire SPG4 interval, we identified a candidate gene encoding a new member of the AAA protein family, which we named spastin. Sequence analysis of this gene in seven SPG4-linked pedigrees revealed several DNA modifications, including missense, nonsense and splice-site mutations. Both SPG4 and its mouse orthologue were shown to be expressed early and ubiquitously in fetal and adult tissues. The sequence homologies and putative subcellular localization of spastin suggest that this ATPase is involved in the assembly or function of nuclear protein complexes.
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PMID:Spastin, a new AAA protein, is altered in the most frequent form of autosomal dominant spastic paraplegia. 1061 Jan 78

We previously reported that the nuclear localization signal (NLS) peptides stimulate the in vitro phosphorylation of several proteins, including a 34 kDa protein. In this study, we show that this specific 34 kDa protein is a novel murine leucine-rich acidic nuclear protein (LANP)-like large protein (mLANP-L). mLANP-L was found to have a basic type NLS. The co-injection of Q69LRan-GTP or SV40 T-antigen NLS peptides prevented the nuclear import of mLANP-L. mLANP-L NLS bound preferentially to Rch1 and NPI-1, but not to the Qip1 subfamily of importin alpha. These findings suggest that mLANP-L is transported into the nucleus by Rch1 and/or NPI-1.
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PMID:Characterization of the nuclear transport of a novel leucine-rich acidic nuclear protein-like protein. 1069 81

Ku is a heterodimeric protein composed of approximately 70- and approximately 80-kDa subunits (Ku70 and Ku80) originally identified as an autoantigen recognized by the sera of patients with autoimmune diseases. Ku has high binding affinity for DNA ends and that is why originally it was known as a DNA end binding protein, but now it is known to also bind the DNA structure at nicks, gaps, hairpins, as well as the ends of telomeres. It has been reported also to bind with sequence specificity to DNA and with weak affinity to RNA. Ku is an abundant nuclear protein and is present in vertebrates, insects, yeast, and worms. Ku contains ssDNA-dependent ATPase and ATP-dependent DNA helicase activities. It is the regulatory subunit of the DNA-dependent protein kinase that phosphorylates many proteins, including SV-40 large T antigen, p53, RNA-polymerase II, RP-A, topoisomerases, hsp90, and many transcription factors such as c-Jun, c-Fos, oct-1, sp-1, c-Myc, TFIID, and many more. It seems to be a multifunctional protein that has been implicated to be involved directly or indirectly in many important cellular metabolic processes such as DNA double-strand break repair, V(D)J recombination of immunoglobulins and T-cell receptor genes, immunoglobulin isotype switching, DNA replication, transcription regulation, regulation of heat shock-induced responses, regulation of the precise structure of telomeric termini, and it also plays a novel role in G2 and M phases of the cell cycle. The mechanism underlying the regulation of all the diverse functions of Ku is still obscure.
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PMID:Ku autoantigen: a multifunctional DNA-binding protein. 1075 64

Epigenetic modifications change transcription patterns in multicellular organisms to achieve tissue-specific gene expression and inactivate alien DNA such as transposons or transgenes. In plants and animals, DNA methylation is involved in heritability and flexibility of epigenetic states, although its function is far from clear. We have isolated an Arabidopsis gene, MOM, whose product is required for the maintenance of transcriptional gene silencing. Mutation of this gene or depletion of its transcript by expression of antisense RNA reactivates transcription from several previously silent, heavily methylated loci. Despite this, the dense methylation at these reactivated loci is maintained even after nine generations, indicating that transcriptional activity and methylation pattern are inherited independently. The predicted MOM gene product is a nuclear protein of 2,001 amino acids containing a region similar to part of the ATPase region of the SWI2/SNF2 family, members of which are involved in chromatin remodelling. MOM is the first known molecular component that is essential for transcriptional gene silencing and does not affect methylation pattern. Thus, it may act downstream of methylation in epigenetic regulation, or be part of a new pathway that does not require methylation marks.
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PMID:Disruption of the plant gene MOM releases transcriptional silencing of methylated genes. 1082 Dec 58

Differential scanning calorimetry was used to study the interactions of nuclei isolated from Chinese hamster V79 cells with the radioprotector WR-1065, other thiol compounds, and polyamines. Differential scanning calorimetry monitors denaturation of macromolecules and resolves the major nuclear components (e.g. constrained and relaxed DNA, nucleosome core, and nuclear matrix) of intact nuclei on the basis of thermal stability. WR-1065 treatment (0.5-10 mM) of isolated nuclei led to the irreversible denaturation of nuclear proteins, a fraction of which are nuclear matrix proteins. Denaturation of 50% of the total nonhistone nuclear protein content of isolated nuclei occurred after exposure to 4.7 mM WR-1065 for 20 min at 23 degrees C. In addition, a 22% increase in the insoluble protein content of nuclei isolated from V79 cells that had been treated with 4 mM WR-1065 for 30 min at 37 degrees C was observed, indicating that WR-1065-induced protein denaturation occurs not only in isolated nuclei but also in the nuclei of intact cells. From the extent of the increase in insoluble protein in the nucleus, protein denaturation by WR-1065 is expected to contribute to drug toxicity at concentrations greater than approximately 4 mM. WR-33278, the disulfide form of WR-1065, was approximately twice as effective as the free thiol at denaturing nuclear proteins. The proposed mechanism for nucleoprotein denaturation is through direct interactions with protein cysteine groups with the formation of destabilizing protein-WR-1065 disulfides. In comparison to its effect on nuclear proteins in isolated nuclei, WR-1065 had only a very small effect on non-nuclear proteins of whole cells, isolated nuclear matrix, or the thiol-rich Ca(2+)ATPase of sarcoplasmic reticulum, indicating that WR-1065 can effectively denature protein only inside an intact nucleus, probably due to the increased concentration of the positively charged drug in the vicinity of DNA.
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PMID:Radioprotective thiolamines WR-1065 and WR-33278 selectively denature nonhistone nuclear proteins. 1082 57

Androgen receptor (AR) belongs to the superfamily of nuclear hormone receptors that employ complex molecular mechanisms to guide the development and physiological functions of their target tissues. Our recent work has led to the identification of four novel proteins that recognize AR zinc-finger region (ZFR) both in vivo and in vitro. One is a small nuclear RING-finger protein that possesses separate interaction interfaces for AR and for other transcription activators such as Sp1. The second is a nuclear serine/threonine protein kinase (androgen-receptor-interacting nuclear protein kinase; ANPK); however, the receptor itself does not seem to be a substrate for this kinase. The third one is dubbed androgen-receptor-interacting protein 3 (ARIP3) and is a novel member of the PIAS (protein inhibitor of activated STAT) protein family. The fourth protein, termed ARIP4, is a nuclear ATPase that belongs to the SNF2-like family of chromatin remodelling proteins. All four proteins exhibit a punctate nuclear pattern when expressed in cultured cells. Each protein modulates AR-dependent transactivation in co-transfection experiments; their activating functions are not restricted to AR. Current work is aimed at elucidating the biochemical and functional properties of these AR-interacting proteins and at finding the partner proteins that form complexes with them in vivo.
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PMID:Androgen-receptor-interacting nuclear proteins. 1096 28


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