ISSN:
1615-6102
Keywords:
Characeae
;
Ca2+
;
Cytoplasmic streaming
;
Protein phosphatase
;
Protein phosphatase inhibitor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The mechanism of Ca2+ regulation of the cytoplasmic streaming in characean cells was studied in relation to protein phosphorylation and dephosphorylation. A tonoplast-free cell model was developed which was sensitive to Ca2+. Protein phosphatase-1 and its inhibitor-1 were applied into the tonoplast-free cells. A synthetic inhibitor of protein phosphatase, α-naphthylphosphate, was applied either to tonoplast-free cells from inside or to the outside of plasmalemma-permeabilized cells which are known to be very sensitive to Ca2+. ATP-γ-S applied to permeabilized cells strongly inhibited the recovery of the streaming which had been stopped by 10 μ M Ca2+. Both inhibitor-l and α-naphthylphosphate inhibited the streaming even in the absence of Ca2+. On the other hand, protein phosphatase-l recovered the streaming even in the presence of Ca2+. The results indicate that characean streaming is regulated by the phosphorylation state of a regulatory and/or motile protein component. Streaming is activated when the component is dephosphorylated and inactivated when the component is phosphorylated. Ca2+ is assumed to stimulate both phosphorylation and dephosphorylation of the component. Involvement of Ca2+/calmodulin in the streaming recovery was discussed in terms of the stimulation of dephosphorylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01276365
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