Transport of 2 aminoisobutyric acid in mesophyll protoplasts of pisum sativum l application of silicone oil layer centrifugation

Borstlap, A.C.; Kuyper Vos, A.A.; Schuurmans, J.

Plant Science 48(1): 55-62

1987


ISSN/ISBN: 0168-9452
DOI: 10.1016/0168-9452(87)90070-7
Accession: 006831274

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Abstract
Uptake of 2-amino[1-14C]isobutyric acid by pea mesophyll protoplasts was investigated using silicone oil layer centrifugation. Uptake was expressed on the basis of the 3H2O-space of the protoplast pellet. The 3H2O-space can be used as a measure of protoplast volume, taking into consideration that about 10% of it is extracellular space. At concentrations in the range 10 .mu.M-10 mM, the uptake of 2-aminoisobutyric acid (Aib) was linear with time for at least 1 h. At an external concentration of 10 .mu.M, up to a 10-fold accumulation of Aib in the protoplasts was observed during 1 h of incubation. The concentration-dependence of the uptake rate conforms to the sum of a Michaelis-Menten term and a linear term. Large differences in uptake rates were found for different preparations of protoplasts, especially at low concentrations of Aib. This could be attributed to differences in the activity of the saturable component. Both transport components were strongly inhibited by 10 .mu.M CCCP, even when transport was apparently downhill.