Chloroplast Inner-Envelope ATPase Acts as a Primary H+ Pump.

AUTOR(ES)

Berkowitz, G. A.

RESUMO

The stromal pH of the chloroplast must be maintained higher than that of the surrounding cytosol for photosynthetic carbon assimilation to occur. Experimental evidence demonstrating how this is accomplished in the plant cell is lacking. In the experiments reported here, we studied H+ and K+ flux across membranes of purified chloroplast inner-envelope vesicles. We were able to demonstrate ATP-dependent transport of both cations across the membranes of these vesicles. The data presented document the presence of an H+-pump ATPase in the chloroplast envelope. Energy-dependent K+ flux across these membranes occurs as a consequence of primary H+ pumping. The H+-pumping activity demonstrated in this report is consistent with a model involving the activity of this envelope ATPase as a primary mechanism facilitating a stroma:cytosol [delta]pH.

Documentos Relacionados

• Direct Measurement of Calcium Transport across Chloroplast Inner-Envelope Vesicles1
• Immunochemical Analysis Shows That an ATP/ADP-Translocator Is Associated with the Inner-Envelope Membranes of Amyloplasts from Acer pseudoplatanus L. 1
• The neurospora plasma membrane ATPase is an electrogenic pump.
• Characterization of a chloroplast inner envelope K+ channel.
• ATP-dependent H+ -pump activity in inverted vesicles of Methanosarcina mazei Gö1 and characterization of membrane ATPase.