Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Although cyclic AMP (cAMP) has been reported to cross talk with the protein kinase C (PKC) system, effects of elevated intracellular cAMP on the activities of specific PKC isoforms have not been studied. We report findings from a permeabilized cell assay that was used to examine changes in the activity of the atypical PKC isoforms brought about by exposure of PC12 cells to agents that elevate intracellular cAMP. We found that increases in intracellular cAMP led to rapid stimulation of atypical PKC activity, 40–70% above control, for a sustained period of time, a response that occurred independent of the phorbol 12-myristate 13-acetate (PMA)-sensitive PKC isoforms. Changes in intracellular cAMP levels resulted in a dose-dependent redistribution of ζ-PKC to the cytoplasm with a concomitant increase in the phosphorylation state of the enzyme. Incubation of purified ζ-PKC with increasing concentrations of PKA likewise caused a twofold increase in the phosphorylation state of ζ-PKC. In contrast to the positive effect that PKA-mediated phosphorylation had on the activity of ζ-PKC, the enzyme displayed reduced binding to ras when phosphorylated. Taken together, these findings are consistent with the hypothesis that protein phosphorylation of PKC acts as a positive effector of its enzyme activity and may serve as a negative modulator for interaction with other proteins.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Nerve growth factor-stimulated mitogen-activated protein kinase (pp42/44MAP) kinase was characterized by sequential column chromatography on DEAE-Sephacel, phenyl-Sepharose CL4B, and S-200. The kinase displayed an apparent molecular mass of 42 kDa and reacted with an antiphosphotyrosine antibody. Peptide mapping of myelin basic protein revealed the presence of one phosphopeptide that was phosphorylated on Thr-97. pp42/44MAP kinase activity was dependent on Mg2+ and inhibited by K252a both in vitro and in vivo. Nerve growth factor-stimulated kinase activation was diminished by down-regulation of protein kinase C with 200 nM 12-phorbol 13-myristate acetate or with staurosporine (1 nM), a protein kinase C inhibitor. Genistein, a protein tyrosine kinase inhibitor, blocked nerve growth factor-mediated neurite extension as well as diminished activation of pp42/44MAP kinase. Our data demonstrate that activation of this kinase system by nerve growth factor displays a requirement for both protein kinase C as well as protein tyrosine kinase. In addition, other agents that are capable of promoting neurite outgrowth in PC12 cells, such as fibroblast growth factor or dibutryl cyclic AMP, do so independently of activating this kinase system.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 94 (2005), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Inclusions isolated from several neurodegenerative diseases, including Alzheimer's disease (AD), are characterized by ubiquitin-positive proteinaceous aggregates. Employing confocal and immunoelectron microscopy, we find that the ubiquitin-associating protein sequestosome1/p62, co-localizes to aggregates isolated from AD but not control brain, along with the E3 ubiquitin ligase, TRAF6. This interaction could be recapitulated by co-transfection in HEK293 cells. Employing both in vitro and in vivo approaches, tau was found to be a substrate of the TRAF6, possessing lysine 63 polyubiquitin chains. Moreover, tau recovered from brain of TRAF6 knockout mice, compared with wild type, was not ubiquitinated. Tau degradation took place through the ubiquitin–proteasome pathway and was dependent upon either the K63-polyubiquitin chains or upon p62. In brain lysates of p62 knockout mice, tau fails to co-interact with Rpt1, a proteasomal subunit, thereby indicating a requirement for p62 shuttling of tau to the proteasome. Our results demonstrate that p62 interacts with K63-polyubiquitinated tau through its UBA domain and serves a novel role in regulating tau proteasomal degradation. We propose a model whereby either a decline in p62 expression or a decrease in proteasome activity may contribute to accumulation of insoluble/aggregated K63-polyubiquitinated tau.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 118 (1984), S. 67-78 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Serum from cystic fibrosis patients has been shown by scanning electron microscopy to cause release of large quantities of mucus from the cultured tracheal rings of 3-4-month-old male Golden Syrian hamsters. In order to study this phenomenon on single cells, an epithelial (HTE) cell culture has been established from the hamster tracheal rings using the cell rescue method of Goldman and Baseman (1980a, In Vitro, 16:313). The cells were demonstrated to be epithelial by histochemical staining and immunofluorescent detection of laminin. Proteins secreted by HTE cells were partially characterized and shown to consist, at least in part, of acidic glycoproteins. The proteins were precipitated by addition of buffered alcian blue (AB) to the cell-free medium under conditions in which all of a polyanionic protein [3H]-labeled mucin, was precipitated without carrier. [14C] galactosamine-labeled AB precipitate was β-eliminated and, after neutralization and centrifugation, the material in the supernatant was sized by chromatography on a calibrated Bio-Gel P2 column. The label eluted with a molecular weight close to a disaccharide. HTE cells pulse--labeled for 1.0 hr with [3H] leucine or [14C] galactosamine secreted increasing amounts of labeled glycoprotein during the chase. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and fluorography of labeled AB precipitates revealed three major bands, two with molecular weights greater than 100 kd. Secretion was stimulated by retinoate (50% increase), but not by retinol. Exposure of HTE cells to whole sera from cystic fibrosis patients resulted in heightened secretion rates as compared to results obtained with normal sera. Heterozygote sera produced secretion rates intermediate between the two extremes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0148-7280
    Keywords: sperm maturation ; protein kinase changes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mammalian spermatozoa have been shown to possess cAMP-dependent protein kinase (A-PK) and endogenous substrate proteins for this enzyme. A study of the kinase system was undertaken to determine changes that may be associated with sperm maturation by comparing immature testicular with mature cauda epididymal and ejaculated spermatozoa. Absolute activity levels of A-PK, stimulated over a concentration range of 10-9 to 10-5 M, was significantly greater in testicular than ejaculated spermatozoa. At an optimal cAMP concentration (10-6M), testicular spermatozoa had significantly greater amounts of cAMP-dependent protein kinase activity than did cauda or ejaculated spermatozoa. Electrophoretic analysis and autoradiography of NP-40-soluble protein extracts revealed the presence of two substrate proteins (Mr = 62,000 and 44,000) in all three types of spermatozoa. In addition, a phosphoprotein (Mr = 20,000) was detected in mature cauda and ejaculated but not immature testicular spermatozoa. The phosphorylation of these substrate proteins was both dose and time dependent. Examination of cyclic AMP phosphodiesterase activity revealed significantly higher levels in testicular than ejaculated spermatozoa. These results indicate marked alterations in cAMP-modulated protein phosphorylation and dephosphorylation systems in ram spermatozoa during epididymal maturation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...