Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Regulation of intracellular pH (pHi) was investigated in Trypanosoma cruzi amastigotes and trypomastigotes using 2',7'-bis-(carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF). pHi was determined to be 7.33 +/- 0.08 and 7.35 +/- 0.07 in amastigotes and trypomastigotes, respectively, and there were no significant differences in the regulation of pH, between the two stages. Steady-state pHi, recovery of pHi from acidification, and H+-efflux were all decreased markedly by the H+-ATPase inhibitors N,N'-dicyclohexylcarbodi-imide (DCCD), diethylstilbestrol (DES) and N-ethylmaleimide (NEM) supporting a significant role for a plasma membrane H+-ATPase in the regulation of pHi. pHi was maintained at neutrality over a range of external pH (pHe) from 5-8 in parasites suspended in a buffer containing Na+ and K+ (standard buffer) but was acidified at low pHe in the absence of these cations (choline buffer). The pHi of trypomastigotes decreased significantly when they transformed into amastigotes. The rate of recovery of pHi by acidified parasites was similar in Na+-free buffer and standard buffer but was slower in the absence of K+ (K+-free or choline buffer) and parasites suspended in choline buffer were acidic by 0.25 pH units as compared with controls. Ba2+ and Cs+ decreased the pHi of parasites suspended in standard but not choline buffer suggesting the presence of an inward directed K+ channel. The pHi of amastigotes and trypomastigotes suspended in Cl(-)-free buffer was decreased by 0.13 and 0.2 pH units, respectively, supporting the presence of a chloride conductive channel. No evidence of pH regulation via a Na+/H+ or Cl-/HCO3- exchanger was found. These results are consistent with the presence of a plasma membrane H+-ATPase that regulates pHi and is supported by K+ and Cl- channels.
Mol Biochem Parasitol 2000 Feb 05
PMID:Intracellular pH in mammalian stages of Trypanosoma cruzi is K+-dependent and regulated by H+-ATPases. 1069 46

In decapod crustaceans, deposition of calcium carbonate crystals (calcification) in the exoskeleton takes place during the postmolt phase of the molt cycle. In an attempt to identify proteins which regulate the calcification process, the differential display technique was used to identify genes which were specifically expressed in the integument during the postmolt stage in the penaeid prawn Penaeus japonicus. One of the genes thus identified, named DD9A, was expressed in the epithelial cells of the tail fan. DD9A encoded a putative precursor of a secreted protein of 113 amino acids which exhibited sequence similarities to a group of crustacean and insect cuticular proteins, suggesting that DD9A was a protein component of the exoskeleton. Another gene, DD9B, which was also transcribed specifically during the postmolt period was identified based on its sequence similarity to DD9A. Potential roles of the DD9A protein in the calcification of the exoskeleton will be discussed.
Comp Biochem Physiol B Biochem Mol Biol 2000 Jan
PMID:Molecular analysis of two genes, DD9A and B, which are expressed during the postmolt stage in the decapod crustacean Penaeus japonicus. 1084 Jun 48

We have characterized LUV1/RKI1/TCS3/VPS54, a novel yeast gene required to maintain normal vacuolar morphology. The luv1 mutant was identified in a genetic screen for mutants requiring the phosphatase calcineurin for vegetative growth. luv1 mutants lack a morphologically intact vacuole and instead accumulate small vesicles that are acidified and contain the vacuolar proteins alkaline phosphatase and carboxypeptidase Y and the vacuolar membrane H(+)-ATPase. Endocytosis appears qualitatively normal in luv1 mutants, but some portion (28%) of carboxypeptidase Y is secreted. luv1 mutants are sensitive to several ions (Zn(2+), Mn(2+), and Cd(2+)) and to pH extremes. These mutants are also sensitive to hygromycin B, caffeine, and FK506, a specific inhibitor of calcineurin. Some vacuolar protein-sorting mutants display similar drug and ion sensitivities, including sensitivity to FK506. Luv1p sediments at 100,000 x g and can be solubilized by salt or carbonate, indicating that it is a peripheral membrane protein. A Green Fluorescent Protein-Luv1 fusion protein colocalizes with the dye FM 4-64 at the endosome, and hemagglutinin-tagged Luv1p colocalizes with the trans-Golgi network/endosomal protease Kex2p. Computer analysis predicts a short coiled-coil domain in Luv1p. We propose that this protein maintains traffic through or the integrity of the early endosome and that this function is required for proper vacuolar morphology.
Mol Biol Cell 2000 Jul
PMID:Luv1p/Rki1p/Tcs3p/Vps54p, a yeast protein that localizes to the late Golgi and early endosome, is required for normal vacuolar morphology. 1088 79

Water has been recognized as one of the major structuring factors in biological macromolecules. Indeed, water clusters influence many aspects of biological function, and the water-protein interaction has long been recognized as a major determinant of chain folding, conformational stability, internal dynamics, binding specificity and catalysis. I discuss here several themes arising from recent progress in understanding structural aspects of 'direct' and 'indirect' ligands in terms of enzyme-substrate interactions, and the role of water bridges in enzyme catalysis. The review also attempts to illuminate issues relating to efficiency, through solvent interactions associated with enzymic specificity, and versatility. Over the years, carbonic anhydrase (CA; carbonate hydrolyase, EC 4.2.1.1) has played a significant role in the continuing delineation of principles underlying the role of water in enzyme reactions. As a result of its pronounced catalytic power and robust constitution CA was transformed into a veritable 'laboratory' in which active site mechanisms were rigorously tested and explored.
Cell Mol Life Sci 2000 Jul
PMID:Water in enzyme reactions: biophysical aspects of hydration-dehydration processes. 1096 41

Although it is clear that osteoporosis is associated with a reduction in bone mass and a fragile skeleton, it is not understood whether the chemical composition of osteoporotic bone is different from normal bone. In this study, cynomolgus monkeys (Macaca fascicularis) were administered fluorochrome labels at one and two years after ovariectomy (Ovx) or Sham ovariectomy (intact), that were taken up into newly remodeled bone. Using fluorescence-assisted synchrotron infrared microspectroscopy, the chemical composition of bone from intact versus Ovx monkeys has been compared. Results from overall composition distributions (labeled + non-labeled bone) reveal similar carbonate/protein and phosphate/protein ratios, but increased acid phosphate content and different collagen structure in the Ovx animals. Analysis of the fluorochrome-labeled bone indicates similar degrees of mineralization in bone remodeled after one year, but decreased mineralization in Ovx bone remodeled two years after surgery. Thus, bone from monkeys with osteoporosis can be characterized as having abnormal collagen structure and reduced rates of mineralization. Coupled with factors such as trabecular architecture and bone shape and size, these ultrastructural factors may play a contributing role in the increased bone fragility in osteoporosis.
Cell Mol Biol (Noisy-le-grand) 2000 Sep
PMID:Examination of bone chemical composition in osteoporosis using fluorescence-assisted synchrotron infrared microspectroscopy. 1097 61

Intracellular pH was measured with the pH-sensitive fluorescent probe BCECF in spinal cord neurones cultured from rat embryos. At an external pH of 7.3, the average steady-state pHi was 7.18 +/- 0.03 (SEM, n = 97) and 7.02 +/- 0.01 (n = 221) in HEPES-buffered and in bicarbonate-buffered medium, respectively. In both external media, pHi was strongly dependent on external pH (pHe). In HEPES-buffered medium, pHi recovery following an acid load induced by transient application of ammonium required external Na+ and was inhibited by amiloride, indicating the presence of a Na+/H+ exchange. Na(+)- and HCO3(-)-dependent, DIDS-sensitive alkalinizing mechanisms also contributed to pHi regulation in CO2/bicarbonate-buffered medium. The presence of an electrogenic Na(+)-HCO3- cotransporter was confirmed by the alkalinizing effect of KCl application. The fact that pHi is lower in CO2/bicarbonate- than in HEPES-buffered medium and the alkalinization observed upon suppression of external Cl- suggest that the acidifying Cl-/HCO3- transporter plays an important role in defining pHi.
Mol Membr Biol
PMID:Intracellular pH regulation in ventral horn neurones cultured from embryonic rat spinal cord. 1098 60

The fish otolith is a hard tissue consisting of calcium carbonate and organic matrices. The matrix proteins play important roles in otolith formation, but little is known about the nature of these proteins. In this study, matrix proteins were extracted from the otoliths of rainbow trout, Oncorhynchus mykiss, and chum salmon, Oncorhynchus keta. EDTA-soluble matrix proteins were separated by SDS-PAGE, revealing two major components in the otoliths of both species with apparent molecular masses of 55 and 43 kDa. N-terminal and some internal amino acid sequences of the 55-kDa otolith matrix protein were determined. A cDNA fragment encoding this protein of O. mykiss was amplified by reverse transcription PCR using two degenerate primers designed from the amino acid sequences. A cDNA encoding this protein was obtained by screening a saccular cDNA library using the amplified cDNA fragment as a probe. Nucleotide sequence analysis revealed that the cDNA clone has a sequence of 2.5 kb and the open reading frame encoding 344 amino acid residues. Northern blot analysis showed that mRNA of this protein is expressed specifically in the sacculus, and consistently during the day.
Comp Biochem Physiol B Biochem Mol Biol 2000 Aug
PMID:Molecular cloning and expression of an otolith matrix protein cDNA from the rainbow trout, Oncorhynchus mykiss. 1102 63

The infrared (IR) and Raman spectra are reported for solutions of lithium perchlorate in propylene carbonate (PC), N,N-dimethylformamide (DMF) and PC + DMF mixtures. The band splittings of symmetric ring deformation for PC and O=CN deformation for DMF suggest that there is a strong interaction between lithium cations and solvent molecules. The solvent molecules have been assigned to two types, the free and complexed molecules. By a comparison of the intensity for the corresponding bands, it has been concluded that Li+ cations are preferentially solvated by DMF molecules in the LiClO4/PC-DMF solutions. This has been explained by the difference in values of donor number.
Spectrochim Acta A Mol Biomol Spectrosc 2000 Oct
PMID:Vibrational spectroscopic studies on ion solvation of lithium perchlorate in propylene carbonate + N,N-dimethylformamide mixtures. 1105 58

The Ca2+ binding of an EDTA-free water-soluble (SM) and -insoluble (IM) organic matrix of the freshwater snail Biomphalaria glabrata was investigated, using a 45Ca2+ autoradiography after SDS-electrophoretical separation and a calcium binding assay. Electrophoresis of the SM showed a considerable amount of Alcian blue and Stains all positive material, regarded as glycosaminoglycans (GAGs) or proteoglycans (PGs). This part of the SM was slightly positive after 45Ca2+ autoradiography at pH 6.8. The Ca2+ binding increased, raising the pH to 7.4 and 8.0 and was especially strong when simulating the real conditions of the extrapallial space with a carbonate buffer of pH 7.4. The Ca2+ binding assay of the IM showed the same pH-dependency that was observed in the SM. The titration of the IM with Ca2+ at pH 8.0 lead to a dissociation constant of 7.5 x 10(-5) M. While Mg2+ displaced 45Ca2+ in the same way as nonradioactive Ca2+, an approximately 400-fold amount of Na+ was necessary to reduce the binding of 45Ca2+ to 50%. The Ca2+ binding of the organic matrix from the B. glabrata shell appears to be a process of low specificity, medium affinity and high pH-dependency. Apparently, acidic carbohydrate-rich PGs are the only calcium binding constituents of the organic shell matrix.
Comp Biochem Physiol B Biochem Mol Biol 2000 Oct
PMID:Calcium binding constituents of the organic shell matrix from the freshwater snail Biomphalaria glabrata. 1107 77

The transepithelial transport of inorganic carbon to endolymph and its subsequent deposition on otoliths were pharmacologically examined by incubating the sacculus containing an otolith with NaH(14)CO(3). Calcium incorporation was also studied. Carbon incorporation into endolymph and otoliths was saturated with increased concentrations of bicarbonate ions in the incubation medium and was followed by the Michaelis-Menten equation with a K(m) of 26.3 mM and 0.4 mM, respectively. Carbon incorporation decreased with an increase in chloride concentrations in the medium. Calcium incorporation was not affected by chloride and bicarbonate ions up to 10 mM. Higher concentrations of bicarbonate ions reduced calcium incorporation into both fractions. Carbon incorporation into endolymph and otoliths was inhibited by acetazolamide, disulfonate stilbenes (DIDS and SITS), thiocyanate, and ouabain. Calcium incorporation was not affected by these inhibitors. Amiloride inhibited carbon incorporation into otoliths alone. These results suggest that HCO(3)(-)-ATPase and Cl(-)/HCO(3)(-)-exchangers are involved in the transepithelial transport of bicarbonate ions to the endolymph. Carbonic anhydrase was also suggested to play a role in carbonate production for otolith calcification.
Comp Biochem Physiol A Mol Integr Physiol 2001 Jan
PMID:Effects of enzyme and anion transport inhibitors on in vitro incorporation of inorganic carbon and calcium into endolymph and otoliths in salmon Oncorhynchus masou. 1113 50


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