Disease relevance of Vha14

• Its deduced translation product is a 124-amino-acid polypeptide sharing 90% identity with the Ms polypeptide and 50% identity with an analogous polypeptide of Saccharomyces cerevisiae, and a more distant similarity to a subunit of the Na(+)-transporting ATPase of Enterococcus hirae [1].

High impact information on Vha14

• The catalytic core of CHRAC, the ATPase ISWI, also mobilized nucleosomes at the expense of energy [2].
• Our results provide direct evidence for a conformational change of the kinesin motor domain during the ATPase cycle [3].
• Kinesin, a microtubule-dependent ATPase, is believed to be involved in anterograde axonal transport [4].
• But in combination with an activating factor removed during the purification, it exhibited microtubule-activated ATPase activity and dynamin-induced bundles showed evidence of ATP-dependent force production [5].
• Cytoplasmic dynein is a microtubule-activated ATPase which produces force towards the minus ends of microtubules [6].

Biological context of Vha14

• In yeast, bafilomycin-sensitive ATPase activity and growth rate correlated with the ability of different constructs to rescue the pH-sensitive conditional-lethal phenotype [7].
• The Dm gene (vha14) is present as a single copy at cytological position 52B on the second chromosome, and gives rise to an mRNA species of 0.65 kb [1].
• Involvement of V-ATPase in the regulation of cell size in the fly's visual system [8].
• The multifunctional Drosophila melanogaster V-ATPase is encoded by a multigene family [9].
• Rad54 is related to the ATPase subunits of chromatin-remodeling factors, whereas Rad51 is related to bacterial RecA [10].

Anatomical context of Vha14

• A complex of Tn-T, Tn-H and tropomyosin inhibited actomyosin ATPase activity and the inhibition was relieved by Tn-C from vertebrate striated muscle in the presence of Ca2+ [11].
• Expression of the latter shows relatively little variation during development, or between adult head, thorax and abdomen, suggesting that the F-subunit is a relatively ubiquitous component of the V-ATPase [1].
• Moreover, vacuolar-type H+-ATPase (V-ATPase) in the optic lobe is thought also to participate in such regulation [8].
• In the visual systems of both fly species V-ATPase was localized immunocytochemically to the compound eye photoreceptors [8].
• For each subunit, the single gene identified previously by microarray, as upregulated and abundant in tubules, is shown to be similarly abundant in other epithelia in which V-ATPases are known to be important; there thus appears to be a single dominant "plasma membrane" V-ATPase holoenzyme in Drosophila [12].

Associations of Vha14 with chemical compounds

• The transparent Malpighian tubule phenotype first identified in lethal alleles of vha55, the gene encoding the B-subunit, is shown to be general to those plasma membrane V-ATPase subunits for which lethal alleles are available, and to be caused by failure to accumulate uric acid crystals [12].
• In Drosophila, the Malpighian (renal) tubule contains large amounts of Na(+),K(+) ATPase that is known biochemically to be exquisitely sensitive to ouabain, yet the intact tissue is almost unaffected by even extraordinary concentrations [13].
• Disassembly of the SNARE complex requires the ATPase N-ethylmaleimide-sensitive fusion protein (NSF) [14].
• The nature of the vesicular uptake of glutamate was similar among all the vertebrates: the specificity for glutamate remained high, transport was energized by a vacuolar (V)-type ATPase, 2-4 mM chloride stimulated uptake three- to sixfold, and Km for glutamate was between 0.5 and 2 mM [15].
• The chromatographically separated 174-kilodalton species from both organisms have been further distinguished through the use of polypeptide-specific antisera; finally, the glycoprotein purified from Drosophila embryos is fully sensitive to limited degradation by endoglycosidase H whereas the ATPase/dATPase polypeptide is completely resistant [16].

Physical interactions of Vha14

• Analysis of NSF mutants reveals residues involved in SNAP binding and ATPase stimulation [17].

Regulatory relationships of Vha14

• Previously, we exchanged two versions of this region (encoded by alternative exon 7s) between the indirect flight muscle myosin isoform (IFI) and an embryonic myosin isoform (EMB) and found, surprisingly, that in vitro solution actin-activated ATPase rates were increased (higher Vmax) by both exon exchanges [18].
• When not bound to cargo, the motor protein kinesin is in an inhibited state that has low microtubule-stimulated ATPase activity [19].
• Cdk phosphorylation of DmORC subunits DmOrc1p and DmOrc2p inhibits the intrinsic ATPase activity of DmORC without affecting ATP binding to DmOrc1p [20].
• The Drosophila melanogaster homologue of an insect calcitonin-like diuretic peptide stimulates V-ATPase activity in fruit fly Malpighian tubules [21].
• Since ATP hydrolysis is a prerequisite for enzyme turnover, it is concluded that phosphorylation modulates the overall catalytic activity of topoisomerase II by stimulating the enzyme's ATPase activity [22].

Other interactions of Vha14

• Characterisation of vha26, the Drosophila gene for a 26 kDa E-subunit of the vacuolar ATPase [23].
• We show that mutations in the ATPalpha alpha and nrv2 beta subunits of the Na+/K+ ATPase cause Drosophila tracheal tubes to have increased lengths and expanded diameters [24].
• The Drosophila melanogaster gene vha14 encoding a 14-kDa F-subunit of the vacuolar ATPase [1].
• Alternative exon-encoded regions of Drosophila myosin heavy chain modulate ATPase rates and actin sliding velocity [25].
• BRM encodes the catalytic ATPase required for chromatin remodeling and SNR1 is a regulatory subunit [26].

Analytical, diagnostic and therapeutic context of Vha14

• We have identified a substrate recognition domain in the C-terminal half of the remodeling ATPase ISWI and determined its structure by X-ray crystallography [27].
• Sequence analysis of lethal haywire alleles revealed the importance of the nucleotide-binding domain, suggesting an essential role for ATPase activity [28].
• The RT PCR approach was used to obtain the nucleotide sequence of the mRNA of a sarco/endoplasmic reticulum calcium transporting ATPase (SERCA) from the cross-striated (phasic) part of the adductor muscle of the deep sea scallop [29].
• Using microarray analysis, we show that heterochromatin in Arabidopsis is determined by transposable elements and related tandem repeats, under the control of the chromatin remodelling ATPase DDM1 (Decrease in DNA Methylation 1) [30].

References