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Permeability changes resulting from virus-cell fusion: temperature-dependence of the contributing processes (1985)

Micklem, K. J. ; Nyaruwe, A. ; Pasternak, C. A.

Springer

Molecular and cellular biochemistry 66 (1985), S. 163-173

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ISSN: 1573-4919

Keywords: membrane fusion ; permeability change ; Sendai virus

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Medicine

Notes: Summary A new assay for membrane fusion, using the fluorescent probe pyrene-sulphonyl-phosphatidyl ethanolamine, has been developed. Fusion between the envelope of Sendai virus and human erythrocytes or Lettre cells has a Q10 of ∼4 at 37° C, increasing to ∼7 at 7 ° C; there is no lag to onset of fusion. Viral neuraminidase has a Q10 of 2.3 between 37° C and 4° C. Its action limits the extent of fusion by causing the elution of virus; this effect is particularly marked at low temperature because of the difference in Q10 for fusion and neuraminidase. The temperature-dependence of the initiation of permeability changes following the removal of inhibitory amounts of Ca2+ is ∼2; thus membrane fusion is the principal temperature-sensitive step during the permeabilization of cells by Sendai virus. A recovery process, by which cells become insensitive to the removal of Ca2+ and which therefore limits the extent of permeabilization, has a Q10 of 7.4 between 37° C and 21° C. It is concluded that the lag to onset of permeability changes is not due to a lag in virus-cell membrane fusion, but to the gradual acquisition of a threshold level of membrane damage; the extent of permeabilization depends on the rate of fusion relative to the rates of neuraminidase and recovery.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00220784

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Effect of Ca2+-antagonists on virally-induced cell-permeability changes (1984)

Micklem, K. J. ; Alder, G. M. ; Pasternak, C. A.

New York, NY [u.a.] : Wiley-Blackwell

Cell Biochemistry and Function 2 (1984), S. 249-253

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ISSN: 0263-6484

Keywords: Calcium ; Ca2+-antagonists ; calmodulin ; calmodulin inhibitors ; intracellular cation changes ; permeability changes ; virally-induced permeability changes ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Sendai virus-mediated permeability changes in cells are affected by extracellular Ca2+ or Mn2+ as follows: the lag period to onset of permeability changes is lengthened and the subsequent extent of leakage is reduced. Drugs that block Ca2+ action in excitable cells, such as verapamil and prenylamine, and drugs that inhibit the action of calmodulin, such as trifluoperazine and R24571, have an effect opposite to that of Ca2+: lag is shortened and extent of leakage is increased. The concentration at which either type of drug shows 50% of maximal effect is similar to the concentration at which 50% of binding by drug to calmodulin is achieved. It is concluded that calmodulin may be involved in protecting cells against virally-mediated membrane damage; alternatively the action of calmodulin-binding drugs may not be as specific as currently thought.

Additional Material: 8 Ill.