K+-conducting ion channel of the chloroplast inner envelope: functional reconstitution into liposomes.

AUTOR(ES)

Wang, X

RESUMO

Potassium flux between the chloroplast stroma and cytoplasm is known to be indirectly linked to H+ countertransport and, hence, stromal pH and photosynthetic capacity. The specific molecular mechanism that facilitates K+ flux across the chloroplast envelope is not known and has been a source of controversy for well over a decade. The objective of this study was to elucidate the nature of this envelope protein. To this end, solubilized protein in detergent extracts of purified chloroplast inner envelope vesicles was reconstituted into artificial liposomes, and cation fluxes into these proteoliposomes were measured. Results of inhibitor studies and counterflux experiments indicated that a K+-conducting ion channel was solubilized and functionally reconstituted into the proteoliposomes. This transport protein may be a nonspecific monovalent cation channel. This report represents a direct demonstration of ion channel activity associated with the limiting (inner) membrane of the chloroplast envelope.

Documentos Relacionados

• Characterization of a chloroplast inner envelope K+ channel.
• The preprotein conducting channel at the inner envelope membrane of plastids
• Pigment-protein complexes from Rhodopseudomonas palustris: isolation, characterization, and reconstitution into liposomes.
• Two types of mechanosensitive channels in the Escherichia coli cell envelope: solubilization and functional reconstitution.
• Ferrous Ion Transport across Chloroplast Inner Envelope Membranes1