Journal Article

Blue Light Inactivates Plasma Membrane H<sup>+</sup>-ATPase in Pulvinar Motor Cells of <i>Phaseolus vulgaris</i> L.

Yoshiji Okazaki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 8, pages 860-868
Published in print August 2002 | ISSN: 0032-0781
Published online August 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf099
Blue Light Inactivates Plasma Membrane H+-ATPase in Pulvinar Motor Cells of Phaseolus vulgaris L.

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Unilateral blue light irradiation induces bending of pulvini of Phaseolus vulgaris towards the source of light. The pulvinar bending is caused by a decrease in turgor pressure of motor cells that are irradiated with blue light. Decrease in the turgor pressure is caused by the net efflux of K+ and counter anions, accompanying membrane depolarization. In the present study the effect of blue light on the activity of plasma membrane H+-ATPase was studied in relation to the membrane depolarization. The activity of the plasma membrane H+-ATPase was measured using protoplast suspensions prepared from laminar pulvini from primary leaves. A pulse of blue light under continuous red light irradiation induced both a transient increase in the external pH and transient inhibition of the vanadate-sensitive ATPase. Continuous blue light irradiation under continuous red light irradiation induced both a sustained increase in the external pH and sustained inhibition of the vanadate-sensitive ATPase. These results show that blue light inhibits the activity of the plasma membrane H+-ATPase. Inactivation of the plasma membrane H+-ATPase supports the membrane depolarization induced by the blue light irradiation.

Keywords: Keywords: Blue light response — H+-ATPase — Motor cells — Phaseolus vulgaris — Protoplasts — Pulvinus.; Abbreviations: H+-ATPase, H+-translocating adenosinetriphosphatase; [K+]apo, apoplastic concentration of K+; MOPS, 3-(N-morpholino)propanesulfonic acid; PMSF, phenylmethylsulfonyl fluoride.

Journal Article.  6980 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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