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)

TorsinA is a widely expressed AAA(+) (ATPases associated with various cellular activities) ATPase of unknown function. Previous studies have described torsinA as a type II protein with a cleavable signal sequence, a single membrane spanning domain, and its C-terminus located in the ER (endoplasmic reticulum) lumen. However, in the present study we show that torsinA is not in fact an integral membrane protein. Instead we find that the mature protein associates peripherally with the ER membrane, most likely through an interaction with an integral membrane protein. Consistent with this model, we provide evidence that the signal peptidase complex cleaves the signal sequence of torsinA, and we show that the region previously suggested to form a transmembrane domain is translocated into the lumen of the ER. The finding that torsinA is a peripheral, and not an integral membrane protein as previously thought, has important implications for understanding the function of this novel ATPase.
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PMID:Biosynthesis of the dystonia-associated AAA+ ATPase torsinA at the endoplasmic reticulum. 1703 84

The plasma membrane of the cereal aleurone layer is the site of perception of germination signals and release of enzymes to the starchy endosperm. Analysis of membrane proteins is challenging due to their hydrophobicity and low abundance; thus, little is known about the membrane proteins involved in seed germination. A membrane fraction highly enriched for the plasma membrane H+-ATPase was prepared from barley aleurone layers by aqueous two-phase partitioning. Because detergent and salt washes did not efficiently remove soluble proteins from the membrane preparations, an alternative procedure was developed, comprising batch reversed-phase chromatography with stepwise elution of hydrophobic proteins by 2-propanol. Proteins in the most hydrophobic fraction were separated by SDS-PAGE and identified by LC-MS/MS and barley EST sequence database search. The method was efficient for enrichment of integral membrane proteins with relatively low levels of soluble contaminating proteins. Forty-six proteins associated with barley aleurone plasma membranes were identified, including proteins with more than 10 transmembrane domains. Among the identified proteins were two new isoforms of the plasma membrane H+-ATPase, two proteins possibly involved in ion-channel regulation, and two proteins of unknown function. This represents the first analysis of membrane proteins involved in seed germination using a proteomics approach.
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PMID:Enrichment and identification of integral membrane proteins from barley aleurone layers by reversed-phase chromatography, SDS-PAGE, and LC-MS/MS. 1708 Oct 62

The vent shrimps, Mirocaris fortunata and Rimicaris exoculata, live in a highly fluctuating thermal environment and undergo frequent temperature bursts. As a first step in the investigation of the response to heat stress, this work aimed to characterize stress proteins in these two species. Complementary deoxyribonucleic acid (cDNA) clones encoding a 70-kDa heat shock protein (HSP) were isolated and characterized from M. fortunata and R. exoculata. The cDNA clones were of 2055 and 1941 base pairs in length, and contained a 2018-bp complete open reading frame (ORF) and a 1785-bp partial coding sequence, respectively. The amino acid sequences corresponding to these ORF are 645 residues in length for M. fortunata and 595 for R. exoculata, and were clearly characterized as members of the HSP70 family. The C-terminal extremity would identify R. exoculata sequence as a cytoplasm HSP70. The relationships between the crustacean HSP70 sequences were examined by two phylogenetic methods, i.e. Maximum Likelihood and Bayesian methods. The resulting trees suggested that M. fortunata sequence may correspond to constitutively expressed HSP70, named HSC70, whereas R. exoculata sequence may correspond to an inducible form of HSP70. The HSP70 sequences from the hydrothermal shrimps proved to be very similar to the other homologous shrimp sequences, except for the presence of an insertion of unknown function in the ATPase domain of R. exoculata sequence.
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PMID:First hsp70 from two hydrothermal vent shrimps, Mirocaris fortunata and Rimicaris exoculata: characterization and sequence analysis. 1709 61

Matrix-producing osteoblasts and bone-resorbing osteoclasts maintain bone homeostasis. Osteoclasts are multinucleated, giant cells of hematopoietic origin formed by the fusion of mononuclear pre-osteoclasts derived from myeloid cells. Fusion-mediated giant cell formation is critical for osteoclast maturation; without it, bone resorption is inefficient. To understand how osteoclasts differ from other myeloid lineage cells, we previously compared global mRNA expression patterns in these cells and identified genes of unknown function predominantly expressed in osteoclasts, one of which is the d2 isoform of vacuolar (H(+)) ATPase (v-ATPase) V(0) domain (Atp6v0d2). Here we show that inactivation of Atp6v0d2 in mice results in markedly increased bone mass due to defective osteoclasts and enhanced bone formation. Atp6v0d2 deficiency did not affect differentiation or the v-ATPase activity of osteoclasts. Rather, Atp6v0d2 was required for efficient pre-osteoclast fusion. Increased bone formation was probably due to osteoblast-extrinsic factors, as Atp6v02 was not expressed in osteoblasts and their differentiation ex vivo was not altered in the absence of Atp6v02. Our results identify Atp6v0d2 as a regulator of osteoclast fusion and bone formation, and provide genetic data showing that it is possible to simultaneously inhibit osteoclast maturation and stimulate bone formation by therapeutically targeting the function of a single gene.
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PMID:v-ATPase V0 subunit d2-deficient mice exhibit impaired osteoclast fusion and increased bone formation. 1715 90

The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endolymph ionic composition and the endocochlear potential. A key protein in the maintenance of the electrochemical composition of the endolymph is the Na,K-ATPase. In this study, we have looked for the presence in the rat inner ear of members of the FXYD protein family, recently identified as tissue-specific modulators of Na,K-ATPase. Only FXYD6 is detected at the protein level. FXYD6 is expressed in various epithelial cells bordering the endolymph space and in the auditory neurons. FXYD6 co-localizes with Na,K-ATPase in the stria vascularis and can be co-immunoprecipitated with Na,K-ATPase. After expression in Xenopus oocytes, FXYD6 associates with Na,K-ATPase alpha1-beta1 and alpha1-beta2 isozymes, which are preferentially expressed in different regions of the inner ear and also with gastric and non-gastric H,K-ATPases. The apparent K(+) and Na(+) affinities of alpha1-beta1 and alpha1-beta2 isozymes are different. Association of FXYD6 with Na,K-ATPase alpha1-beta1 isozymes slightly decreases their apparent K(+) affinity and significantly decreases their apparent Na(+) affinity. On the other hand, association with alpha1-beta2 isozymes increases their apparent K(+) and Na(+) affinity. The effects of FXYD6 on the apparent Na(+) affinity of Na,K-ATPase and the voltage dependence of its K(+) effect are distinct from other FXYD proteins. In conclusion, this study defines the last FXYD protein of unknown function as a modulator of Na,K-ATPase. Among FXYD protein, FXYD6 is unique in its expression in the inner ear, suggesting a role in endolymph composition.
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PMID:FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear. 1720 44

MutS homologues are highly conserved enzymes engaged in DNA mismatch repair (MMR), meiotic recombination and other DNA modifications. Genome sequencing projects have revealed that bacteria and plants possess a MutS homologue, MutS2. MutS2 lacks the mismatch-recognition domain of MutS, but contains an extra C-terminal region called the small MutS-related (Smr) domain. Sequences homologous to the Smr domain are annotated as 'proteins of unknown function' in various organisms ranging from bacteria to human. Although recent in vivo studies indicate that MutS2 plays an important role in recombinational events, there had been only limited characterization of the biochemical function of MutS2 and the Smr domain. We previously established that Thermus thermophilus MutS2 (ttMutS2) possesses endonuclease activity. In this study, we report that a Smr-deleted ttMutS2 mutant retains the dimerization, ATPase and DNA-binding activities, but has no endonuclease activity. Furthermore, the Smr domain alone was stable and functional in binding and incising DNA. It is noteworthy that an endonuclease activity is associated with a MutS homologue, which is generally thought to recognize specific DNA structures.
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PMID:Nuclease activity of the MutS homologue MutS2 from Thermus thermophilus is confined to the Smr domain. 1721 94

Transcription of protein-coding genes in Leishmania major and other trypanosomatids differs from that in most eukaryotes and bioinformatic analyses have failed to identify several components of the RNA polymerase (RNAP) complexes. To increase our knowledge about this basic cellular process, we used tandem affinity purification (TAP) to identify subunits of RNAP II and III. Mass spectrometric analysis of the complexes co-purified with TAP-tagged LmRPB2 (encoded by LmjF31.0160) identified seven RNAP II subunits: RPB1, RPB2, RPB3, RPB5, RPB7, RPB10 and RPB11. With the exception of RPB10 and RPB11, and the addition of RPB8, these were also identified using TAP-tagged constructs of one (encoded by LmjF34.0890) of the two LmRPB6 orthologues. The latter experiments also identified the RNAP III subunits RPC1 (C160), RPC2 (C128), RPC3 (C82), RPC4 (C53), RPC5 (C37), RPC6 (C34), RPC9 (C17), RPAC1 (AC40) and RPAC2 (AC19). Significantly, the complexes precipitated by TAP-tagged LmRPB6 did not contain any RNAP I-specific subunits, suggesting that, unlike in other eukaryotes, LmRPB6 is not shared by all three polymerases but is restricted to RNAP II and III, while the LmRPB6z (encoded by LmjF25.0140) isoform is limited to RNAP I. Similarly, we identified peptides from only one (encoded by LmjF18.0780) of the two RPB5 orthologues and one (LmjF13.1120) of the two RPB10 orthologues, suggesting that LmRPB5z (LmjF18.0790) and LmRPB10z (LmjF13.1120) are also restricted to RNAP I. In addition to these RNAP subunits, we also identified a number of other proteins that co-purified with the RNAP II and III complexes, including a potential transcription factor, several histones, an ATPase involved in chromosome segregation, an endonuclease, four helicases, RNA splicing factor PTSR-1, at least two RNA binding proteins and several proteins of unknown function.
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PMID:Characterization of the RNA polymerase II and III complexes in Leishmania major. 1727 24

Cells of the dopaminergically innervated salivary ducts in the cockroach Periplaneta americana have a vacuolar-type H(+)-ATPase (V-ATPase) of unknown function in their apical membrane. We have studied whether dopamine affects intracellular pH (pH(i)) in duct cells and whether and to what extent the apical V-ATPase contributes to pH(i) regulation. pH(i) measurements with double-barrelled pH-sensitive microelectrodes and the fluorescent dye BCECF have revealed: (1) the steady-state pH(i) is 7.3+/-0.1; (2) dopamine induces a dose-dependent acidification up to pH 6.9+/-0.1 at 1 micromol l(-1) dopamine, EC(50) at 30 nmol l(-1) dopamine; (3) V-ATPase inhibition with concanamycin A or Na(+)-free physiological saline (PS) does not affect the steady-state pH(i); (4) concanamycin A, Na(+) -free PS and Na(+)/H(+) exchange inhibition with 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) each reduce the rate of pH(i) recovery from a dopamine-induced acidification or an acidification induced by an NH(4)Cl pulse; (5) pH(i) recovery after NH(4)Cl-induced acidification is almost completely blocked by concanamycin A in Na(+)-free PS or by concanamycin A applied together with EIPA; (6) pH(i) recovery after dopamine-induced acidification is also completely blocked by concanamycin A in Na(+)-free PS but only partially blocked by concanamycin A applied together with EIPA. We therefore conclude that the apical V-ATPase and a basolateral Na(+)/H(+) exchange play a minor role in steady-state pH(i) regulation but contribute both to H(+) extrusion after an acute dopamine- or NH(4)Cl-induced acid load.
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PMID:A vacuolar-type H+-ATPase and a Na+/H+ exchanger contribute to intracellular pH regulation in cockroach salivary ducts. 1740 Nov 29

To be able to function as a probiotic, bacteria have to survive the passage through the gastrointestinal tract. We have examined survival and gene expression of Lactobacillus reuteri ATCC 55730 after a sudden shift in environmental acidity to a pH close to the conditions in the human stomach. More than 80% of the L. reuteri cells survived at pH 2.7 for 1 h. A genomewide expression analysis experiment using microarrays displayed 72 differentially expressed genes at this pH. The early response to severe acid shock in L. reuteri differed from long-term acid adaptation to milder acid stress studied in other lactic acid bacteria. The genes induced included the following: clpL, genes putatively involved in alterations of the cell membrane and the cell wall; genes encoding transcriptional regulators; phage genes; and genes of unknown function. Two genes, clpL, encoding an ATPase with chaperone activity, and lr1516, encoding a putative esterase, were selected for mutation analyses. The mutants were significantly more sensitive to acid than the wild type was. Thus, these genes could contribute to the survival of L. reuteri in the gastrointestinal tract.
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PMID:The early response to acid shock in Lactobacillus reuteri involves the ClpL chaperone and a putative cell wall-altering esterase. 1744 83

Corynebacteria form an important part of the red smear cheese microbial surface consortium. To gain a better understanding of molecular adaptation due to low pH induced by lactose fermentation, the global gene expression profile of Corynebacterium glutamicum adapted to pH 5.7 with lactic acid under continuous growth in a chemostat was characterized by DNA microarray analysis. Expression of a total of 116 genes was increased and that of 90 genes was decreased compared to pH 7.5 without lactic acid, representing 7% of the genes in the genome. The up-regulated genes encode mainly transcriptional regulators, proteins responsible for export, import, and metabolism, and several proteins of unknown function. As much as 45% of the up-regulated open reading frames code for hypothetical proteins. These results were validated using real-time reverse transcription-PCR. To characterize the functions of 38 up-regulated genes, 36 single-crossover disruption mutants were generated and analyzed for their lactic acid sensitivities. However, only a sigB knockout mutant showed a highly significant negative effect on growth at low pH, suggesting a function in organic-acid adaptation. A sigE mutant already displayed growth retardation at neutral pH but grew better at acidic pH than the sigB mutant. The lack of acid-sensitive phenotypes in 34 out of 36 disrupted genes suggests either a considerable redundancy in acid adaptation response or coincidental effects. Other up-regulated genes included genes for ion transporters and metabolic pathways, including carbohydrate and respiratory metabolism. The enhanced expression of the nrd (ribonucleotide reductase) operon and a DNA ATPase repair protein implies a cellular response to combat acid-induced DNA damage. Surprisingly, multiple iron uptake systems (totaling 15% of the genes induced >or=2-fold) were induced at low pH. This induction was shown to be coincidental and could be attributed to iron-sequestering effects in complex media at low pH.
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PMID:Gene expression analysis of Corynebacterium glutamicum subjected to long-term lactic acid adaptation. 1752 6


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