ATP- and growth substance-dependent cell-free enlargement of plasma membrane vesicles from soybean
Titel:
ATP- and growth substance-dependent cell-free enlargement of plasma membrane vesicles from soybean
Auteur:
Auderset, Guy Morré, D. James
Verschenen in:
BioFactors
Paginering:
Jaargang 28 (2007) nr. 2 pagina's 83-90
Jaar:
2007-03-21
Inhoud:
Growth hormone-responsive and nucleoside triphosphate-dependent enlargement of inside-out vesicles of plasma membranes from soybeans prepared by aqueous two-phase partition and everted by freezing and thawing has been achieved in a cell-free system. In the presence of 100 μM ATP in 40 mM HEPES buffer, pH 7, enlargement of isolated plasma membrane vesicles was accelerated by the synthetic plant growth factor, 2,4-dichlorophenoxyacetic acid (2,4-D), compared to ATP alone, 2,4-D alone or no additions. After 20 min with 1 μM 2,4-D, vesicles increased in diameter, 20% on average. Although vesicle diameters in the presence or absence of 2,4-D overlapped, the means were clearly separated. The 20% increases in diameter corresponded to a doubling of vesicle volume. Both 100 μM ATP and 1 μM 2,4-D were necessary to stimulate the cell-free vesicle enlargement. In the presence of 1 μM 2,4-D, enlargement observed with 100 μM ATP was greater than with either 10 μM ATP or 500 μM ATP alone. In the presence of 100 μM ATP, vesicle enlargement was proportional to the logarithm of 2,4-D concentration. With the growth-inactive 2,4-D analog, 2,3-D, no vesicle enlargement was observed either alone or in the presence of 100 μM ATP. Right side-out vesicles did not enlarge in response to either ATP, 2,4-D or the two in combination suggesting that the responsible ATP site was on the inside of the cell.
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