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Inside‐out but not right side‐out plasma membrane vesicles from soybean enlarge when treated with ATP + 2,4‐D as determined by electron microscopy and light scattering: Evidence for involvement of a plasma membrane AAA‐ATPase
Author(s) -
HicksBergera Carrie,
Morreb D. James
Publication year - 2006
Publication title -
biofactors
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 94
eISSN - 1872-8081
pISSN - 0951-6433
DOI - 10.1002/biof.5520280204
Subject(s) - membrane , vesicle , atpase , chemistry , biophysics , biochemistry , atp synthase , v atpase , cell growth , cell , microbiology and biotechnology , biology , enzyme
The concept that the location of an AAA‐ATPase associated with the plant plasma membrane may be indicative of a functional relationship to growth or cell enlargement by analogy with roles in physical membrane displacements as proposed for AAA‐ATPases associated with internal membranes was tested. A plant growth hormone‐responsive and nucleoside triphosphate‐dependent enlargement of inside‐out vesicles of plasma membranes from soybeans was utilized in a completely cell‐free system. The rate of enlargement was accelerated by the synthetic plant growth factor 2,4‐dichlorophenoxyacetic acid (2,4‐D) in a log dose‐dependent manner and was increased approximately 2‐fold with the addition of 1 μM 2,4‐D plus 100 μM ATP compared to 100 μM ATP alone, 1 μM 2,4‐D alone or no additions. The cell‐free enlargement was inhibited by AAA‐ATPase‐specific antisera and by CoCl2, an inhibitor specific for AAA‐ATPases. The responsible ATP site appears to be on the inside of the cell, since right side‐out vesicles did not enlarge in response to either ATP, 2,4‐D or the two in combination.