THE ARACHIDONATE-ACTIVABLE, NADPH OXIDASE-ASSOCIATED H+ CHANNEL - EVIDENCE THAT GP91-PHOX FUNCTIONS AS AN ESSENTIAL PART OF THE CHANNEL

The human neutrophil NADPH oxidase-associated H+ channel acts as a charge compensator for the electrogenic generation of superoxide (O-2(.-)). The expression of the channel activity was found to increase in parallel with that of the stimulatable generation of O-2(.-) in differentiated HL60 cells, HL60 cells induced to differentiate in the presence of succinyl acetone (a inhibitor of heme synthesis) were unable to generate O-2(.-), failed to express p22-phox but retained H+ channel activity. EBV transformed B lymphocyte cell lines from normal and CGD patients lacking expression of either p47-phox or p67-phox all expressed unaltered channel activity; however, the activity was completely absent in the lymphocyte cell line lacking gp91-phox. CHO cells and undifferentiated HL60 cells transfected with gp91-phox cDNA expressed H+ channel activity correlating with the expression of gp91-phox. We therefore conclude that the large subunit of the NADPH oxidase cytochrome b (gp91-phox) is the arachidonate activable H+ channel of human neutrophils.