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  • 1
    Electronic Resource
    Electronic Resource
    Posttranslational Modification of Calmodulin in Rat Brain and Pituitary (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The posttranslational modification of calmodulin has been studied in six brain regions and the anterior pituitary. Carboxylmethylation, calmodulin converting enzyme, and calmodulin (lysine) N-methyltransferase activities were determined. Incubation of calmodulin with cytosolic extracts of these tissues in the presence of the methyl donor [methyl-3H]-S-adenosyl-l-methionine and identification of labeled proteins by gel electrophoresis and fluorography indicated that calmodulin is a substrate for protein carboxylmethyltransferase in all tissues tested. In hippocampus, caudate nucleus, cerebral cortex, and anterior pituitary, but not in cerebellum, superior colliculus, brainstem, or diencephalon, a second methylated protein was found when calmodulin was added to incubation mixtures. This protein was shown to be identical to the previously described product of calmodulin converting enzyme. Converted calmodulin was isolated by fast protein liquid chromatography and shown to be des(Lys)calmodulin, lacking the carboxy terminal lysine residue of calmodulin. The anterior pituitary had by far the highest levels of calmodulin converting enzyme; this enzyme, in turn, was identified as a cobaltstimulated carboxylpeptidase B. In contrast to the regional differences in these parameters, the levels of calmodulin (lysine) N-methyltransferase did not differ greatly among brain regions, although regional differences in the activity of this enzyme were statistically significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb02845.x
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro phosphorylation of Paramecium axonemes and permeabilized cells (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 1-11 
    Details
    ISSN: 0886-1544
    Keywords: ciliary motility ; cAMP ; Ca2+ ; phosphoproteins ; signal transduction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study seeks to identity phosphoproteins in axonemes from Paramecium letraurelia whose phosphorylation responses to adenosine 3′,5′-cyclic monophosphate (cAMP) and Ca2+ parallel responses induced by these agents in ciliary behavior in this cell. In purified rxonemes, over 15 bands ranging from Mr 〉300 kDa to 19 kDa on SDS-PAGE incorporate 32P from adenosine 5′-γ-[32P]tri-phosphate (γ-32P-ATP) at pCa 7 in the absence of cAMP. A major band whose label turns over rapidly was identified at Mr 43 kDa. In the presence of 5 μM cAMP, more than eight bands, but not the Mr 43 kDa band, were labeled additionally or enhanced their labeling. These phosphoproteins and their kinases are structural components of the axoneme. Overall, some of the same major bands are labeled in the presence of cAMP in Triton X-100-permeabilized paramecia that retain their behavioral responses and in axonemes mechanically isolated from these cells. In particular, two major bands have been identified whose phosphorylation is greatly enhanced by cAMP at low concentrations: (1) a 29 kDa polypeptide whose cAMP-dependent phosphorylation is diminished at pCa 4 compared with pCa 7 and (2) a 65 kDa polypeptide whose phosphorylation is pCa insensitive. These polypeptides meet minimal criteria for signal-sensitive regulators of motility parameters in the Paramecium axoneme.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970120102
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  • 3
    Electronic Resource
    Electronic Resource
    Aspects of signal transduction in stimulus exocytosis-coupling in Paramecium (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 429-443 
    Details
    ISSN: 0730-2312
    Keywords: secretion ; cell membrane ; calcium channels ; membrane fusion ; phosphoproteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: This paper deals with the detailed mechanisms of signal transduction that lead to exocytosis during regulative secretion induced by specific secretagogues in a eukaryotic cell, Paramecium tetraurelia. There are at least three cellular compartments involved in the process: (I) the plasma membrane, which contains secretagogue receptors and other transmembrane proteins, (II) the cytoplasm, particularly in the region between the cell and secretory vesicle membranes, where molecules may influence interactions of the membranes, and (III) the secretory vesicle itself.The ciliated protozoan Paramecium tetraurelia is very well suited for the study of signal transduction events associated with exocystosis because this eukaryotic cell contains thousands of docked secretory vesicles (trychocysts) below the cell membrane which can be induced to release synchronously when trioggered with secretagogue. This ensures a high signal-to-noise ratio for events associated with this process. Upon release the trichocyst membrane fuses with the cell membrane fuses with the cell membrane and the trichocyst content undergoes a Ca2+-dependent irreversible expansion. Secretory mutants are available which are blocked at different points in the signal transduction pathway.Aspects of the three components mentioned above that will be discussed here include (a) the properties of the vesicle content, its pH, and its membrane; (b) the role of phosphorylation/dephosphorylation of a cytosolic 63-kilodalton (kDa)Mr protein in membrane fusion; and (c) how influx of extracellular Ca2+ required for exocytosis may take place via exocytic Ca2+ channels which may be associated with specific membrane microdomains (fusion rosettes).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360411
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