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Dipeptide transport in barley mesophyll vacuoles
A Jamaï1, C Gaillard, S Delrot
1Laboratoire de Physiologie et Biochimie Végétales, Unité Associée CNRS 574, Université de Poitiers, France.
Planta
|January 1, 1995
Summary
This study investigated glycyl-glycine (Gly-Gly) transport in barley vacuoles. ATP energizes Gly-Gly uptake, suggesting an active transport mechanism distinct from proton pumps.
Area of Science:
- Plant Cell Biology
- Molecular Transport
- Biochemistry
Background:
- Vacuolar transport is crucial for plant cell homeostasis.
- Dipeptide transport mechanisms remain incompletely understood.
- Barley vacuoles serve as a model for studying tonoplast transport.
Purpose of the Study:
- To characterize the transport of glycyl-glycine (Gly-Gly) across the tonoplast of isolated barley vacuoles.
- To elucidate the energy dependence and molecular characteristics of Gly-Gly uptake.
Main Methods:
- Utilized isolated barley mesophyll vacuoles for transport assays.
- Investigated the effects of ATP, Mg2+, and specific inhibitors on Gly-Gly uptake.
- Determined kinetic parameters (Km) and substrate specificity.
Main Results:
- ATP significantly enhanced Gly-Gly uptake, indicating an active transport process.
- Mg2+ inhibited ATP-dependent Gly-Gly transport.
- Transport exhibited saturation kinetics with an apparent Km of 49 +/- 5 mM.
- Uptake was sensitive to sulfhydryl reagents and inhibited by other dipeptides and phenylalanine.
Conclusions:
- Glycyl-glycine transport across the barley tonoplast is an ATP-dependent process.
- The transport system appears to be shared with certain amino acids and inorganic ions.
- Findings suggest a novel active transporter for dipeptides in plant vacuoles.