Abstract:
:Bovine adrenal medullary cells, cultured on quartz plates, were superfused with buffer to which pulses of stimulant were added. Cytosolic Ca2+ was measured by the fura-2 fluorescence method and the simultaneously released catecholamine was measured electrochemically. When stimulant concentrations were adjusted to given equivalent elevations of cytosolic Ca2+, secretion depended entirely on whether Ca2+ came from internal stores or from the extracellular medium. Calcium from internal stores did not support secretion under these conditions. This nonequivalence of the two sources of cytosolic Ca2+ points to important differences in the physiological roles of the two sources of calcium. Dimethylphenylpiperazinium (a cholinergic agonist) and elevated K+ increased cytosolic Ca2+ and caused secretion only in the presence of external Ca2+. Bradykinin, muscarine, and ATP elevated cytosolic Ca2+ in the presence and absence of extracellular Ca2+ but caused secretion only in the presence of extracellular Ca2+. UTP, which in the absence of extracellular Ca2+ elevated cytosolic Ca2+ as effectively as ATP, did not cause detectable secretion under any circumstance. Because of the high Ca2+-buffering capacity of the cytosol, we expected that Ca2+ gradients, perhaps quite steep, would be produced by a pulse of Ca2+ entering the cytosol. Fura-2 fluorescence measures only the average free cytosolic Ca2+. Our data show that Ca2+ entering across the plasma membrane was much more effective at triggering exocytosis than was Ca2+ released from internal stores, suggesting that the two sources of Ca2+ are effectively compartmentalized, probably by concentration gradients in the cytosol.
journal_name
Proc Natl Acad Sci U S Aauthors
Kim KT,Westhead EWdoi
10.1073/pnas.86.24.9881subject
Has Abstractpub_date
1989-12-01 00:00:00pages
9881-5issue
24eissn
0027-8424issn
1091-6490journal_volume
86pub_type
杂志文章abstract::Reducing monosaccharides and oligosaccharides, after reductive amination, were separated and detected as their 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde (CBQCA) derivatives by capillary electrophoresis/laser-induced fluorescence. Under optimized conditions, the minimum detectable quantities for monosaccharide sol...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.6.2302
更新日期:1991-03-15 00:00:00
abstract::Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we rep...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.13.5922
更新日期:1994-06-21 00:00:00
abstract::Thioredoxins are 12-kDa proteins functional in the regulation of cellular processes throughout the animal, plant, and microbial kingdoms. Growing evidence with seeds suggests that an h-type of thioredoxin, reduced by NADPH via NADP-thioredoxin reductase, reduces disulfide bonds of target proteins and thereby acts as a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.071041998
更新日期:2001-04-10 00:00:00
abstract::Agrobacterium tumefaciens transfers the T-DNA portion of its Ti plasmid to the nuclear genome of plant cells. Upon cocultivation of A. tumefaciens strain A348 with regenerating tobacco leaf protoplasts, restriction endonuclease fragments of the T-DNA were generated that are consistent with double-stranded cleavage of ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.7.1881
更新日期:1987-04-01 00:00:00
abstract::Engagement of high-affinity IgE receptors leads to activation of tyrosine and serine/threonine kinases and the immediate phosphorylation of receptor beta (serine and tyrosine) and gamma (threonine and tyrosine) chains. Receptor disengagement leads to dephosphorylation of beta and gamma chains via the action of undefin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.22.10733
更新日期:1992-11-15 00:00:00
abstract::Autoimmunity often involves the abnormal targeting of self-antigens by antibodies, leading to tissue destruction and other pathologies. This process could potentially be disrupted by small ligands that bind specifically to autoantibodies and inhibit their interaction with the target antigen. Here we report the identif...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.6.2355
更新日期:1995-03-14 00:00:00
abstract::The decrease with age of the adrenal-secreted dehydroepiandrosterone sulfate (DHEAS) in serum has suggested that it may be causally related to longevity. For the PAQUID [People (Personnes) Aged (Agées) About What (Quid, in Latin)] cohort of elderly subjects, we have previously reported higher DHEAS in men than in wome...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.121177998
更新日期:2001-07-03 00:00:00
abstract::The functional unit molecular size of the intestinal brush border membrane-bound Na+/glucose cotransporter was determined by radiation inactivation. Purified brush border membrane vesicles preserved in cryoprotectant buffer were irradiated (-135 degrees C) with high-energy electrons from a 13-MeV (1 eV = 1.602 x 10(-1...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.4.1456
更新日期:1990-02-01 00:00:00
abstract::Identification of the consensus sequence for termination of replication (ter) in Escherichia coli and the isolation of the ter-binding protein (TBP) allowed us to test their effects on replication forks initiated at the unique origin of the E. coli chromosome (oriC) in a purified enzyme system. Replication was severel...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.86.23.9104
更新日期:1989-12-01 00:00:00
abstract::Mutations in Cu, Zn superoxide dismutase (SOD1) cause the neurodegenerative disease familial amyotrophic lateral sclerosis from an as-yet-unidentified toxic property(ies). Analysis in Saccharomyces cerevisiae of a broad range of human familial amyotrophic lateral sclerosis-linked SOD1 mutants (A4V, G37R, G41D, H46R, H...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.11.6361
更新日期:1998-05-26 00:00:00
abstract::Unconventional myosin 15 is a molecular motor expressed in inner ear hair cells that transports protein cargos within developing mechanosensory stereocilia. Mutations of myosin 15 cause profound hearing loss in humans and mice; however, the properties of this motor and its regulation within the stereocilia organelle a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1409459111
更新日期:2014-08-26 00:00:00
abstract::The configurations of the hydrocarbon chains in micelles are severely constrained by the space-filling requirements of the chain segments, by the continuity of the chains, and by the micellar geometry. A statistical theory that takes full account of these constraints is developed by using a lattice model. The chain en...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.78.2.676
更新日期:1981-02-01 00:00:00
abstract::Obesity is a major health problem worldwide, given its growing incidence and its association with a variety of comorbidities. Weight gain results from an increase in energy intake without a concomitant increase in energy expenditure. To combat the obesity epidemic, many studies have focused on the pathways underlying ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2008919117
更新日期:2020-09-08 00:00:00
abstract::Pore-forming toxins (PFTs) are a class of proteins implicated in a wide range of virulent bacterial infections and diseases. These toxins bind to target membranes and subsequently oligomerize to form functional pores that eventually lead to cell lysis. While the protein undergoes large conformational changes on the bi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1821897116
更新日期:2019-06-25 00:00:00
abstract::Purine nucleoside analogs modified by replacement of the nitrogen atom at the 3 position by a CH group give a characteristic circular dichroism curve that is not substantially modified by chemical substitution at the 8 position. Since it is rather well established that 8-substituted purine nucleosides are predominantl...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.7.2384
更新日期:1976-07-01 00:00:00
abstract::We have cloned and completely sequenced a gene encoding the heavy chain of Dictyostelium myosin I. Like the myosin I molecules from Acanthamoeba, the Dictyostelium myosin I heavy chain is composed of a globular head domain fused to a 45-kDa glycine-, proline-, and alanine-rich carboxyl-terminal domain, rather than the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.86.16.6186
更新日期:1989-08-01 00:00:00
abstract::Chloroplast DNA (cpDNA) is under great photooxidative stress, yet its evolution is very conservative compared with nuclear or mitochondrial genomes. It can be expected that DNA repair mechanisms play important roles in cpDNA survival and evolution, but they are poorly understood. To gain insight into how the most seve...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1004326107
更新日期:2010-08-03 00:00:00
abstract::In a posterior silk gland extract, covalently closed circular (ccc) DNA is in a superhelical state that supports more transcription of fibroin gene than does linear DNA. A HeLa cell extract showed neither the supercoiling activity nor the preference for the transcription of ccc DNA over linear DNA. These activities co...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.3.718
更新日期:1988-02-01 00:00:00
abstract::In this study we sought to better understand the role of the glycoprotein quality control machinery in the assembly of MHC class I molecules with high-affinity peptides. The lectin-like chaperone calreticulin (CRT) and the thiol oxidoreductase ERp57 participate in the final step of this process as part of the peptide-...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1102524108
更新日期:2011-03-22 00:00:00
abstract::The patterns of variations in fisheries time series are known to result from a complex combination of species and fisheries dynamics all coupled with environmental forcing (including climate, trophic interactions, etc.). Disentangling the relative effects of these factors has been a major goal of fisheries science for...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0709034105
更新日期:2008-04-08 00:00:00
abstract::[3H]Puromycin and N-(ethyl-2-diazomalonyl)[3H]puromycin are incorporated into E. coli ribosomes on irradiation at 253.7 nm. Both compounds incorporate into both protein and nucleic acid. Two-dimensional gel electrophoresis of ribosomal protein shows that L23 is the major protein labeled by puromycin. Although incorpor...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.72.8.2974
更新日期:1975-08-01 00:00:00
abstract::Mitochondrial carriers are believed widely to be homodimers both in the inner membrane of the organelle and in detergents. The dimensions and molecular masses of the detergent and protein-detergent micelles were measured for yeast ADP/ATP carriers in a range of different detergents. The radius of the carrier at the mi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0607640103
更新日期:2006-10-31 00:00:00
abstract::The proapoptotic activity of the "BH3-only" molecule BAD can be differentially regulated by survival factor signaling. Bad-deficient mice lacking both BAD long and BAD short proteins proved viable, and most cell types appeared to develop normally. BAD did not exclusively account for cell death after withdrawal of surv...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1533446100
更新日期:2003-08-05 00:00:00
abstract::Thymidine dinucleotide (pTpT) stimulates melanogenesis in mammalian pigment cells and intact skin, mimicking the effects of UV irradiation and UV-mimetic DNA damage. Here it is shown that, in addition to tanning, pTpT induces a second photoprotective response, enhanced repair of UV-induced DNA damage. This enhanced re...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.23.12627
更新日期:1997-11-11 00:00:00
abstract::The mouse sperm receptor, a glycoprotein called ZP3, is synthesized and secreted by growing oocytes. It is present in more than a billion copies in the unfertilized egg's extracellular coat, or zona pellucida. We have cloned and characterized a region of the mouse (CD-1) genome that spans 10 kilobases of the ZP3 locus...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.17.6409
更新日期:1988-09-01 00:00:00
abstract::An enzyme from Saccharomyces cerevisiae that cleaves Holliday junctions was partially purified approximately 500- to 1000-fold by DEAE-cellulose chromatography, gel filtration on Sephacryl S300, and chromatography on single-stranded DNA-cellulose. The partially purified enzyme did not have any detectable nuclease acti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.21.7247
更新日期:1985-11-01 00:00:00
abstract::A major challenge of cancer immunotherapy is the persistence and outgrowth of subpopulations that lose expression of the target antigen. IL-15 is a potent cytokine that can promote organ-specific autoimmunity when up-regulated on tissue cells. Here we report that T cells eradicated 2-wk-old solid tumors that expressed...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1301022110
更新日期:2013-05-14 00:00:00
abstract::Levels and subcellular distribution of connexin 43 (Cx43), a gap junction protein, were studied in hamster leukocytes before and after activation with endotoxin (lipopolysaccharide, LPS) both in vitro and in vivo. Untreated leukocytes did not express Cx43. However, Cx43 was clearly detectable by indirect immunofluores...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.15.7011
更新日期:1995-07-18 00:00:00
abstract::Some realistic galaxy models have been found to support discrete unstable spiral modes. Here, through the study of the relevant physical mechanisms and an extensive numerical investigation of the properties of the dominant modes in a wide class of galactic equilibria, we show how spiral structures are excited with dif...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.12.3908
更新日期:1982-06-01 00:00:00
abstract::The study of the metabolome presents numerous challenges, first among them being the cataloging of its constituents. A step in this direction will be the development of tools to identify metabolites that share common structural features. The importance of sulfated molecules in cell-cell communication motivated us to d...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.252514899
更新日期:2002-12-24 00:00:00