Abstract
The human neutrophil NADPH oxidase-associated H+ channel acts as a charge compensator for the electrogenic generation of superoxide (O2-.). The expression of the channel activity was found to increase in parallel with that of the stimulatable generation of O2-. in differentiated HL60 cells. HL60 cells induced to differentiate in the presence of succinyl acetone (a inhibitor of heme synthesis) were unable to generate O2-., 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.
Highlights
From the Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BSB lTD, United Kingdom
CHO cells and undifferentiated HL60 cells transfected with gp91-phox eDNA expressed H+ channel activity correlating with the expression of gp91-phox
We have investigated the involvement of the oxidase components in the H+ channel activity and have shown that the expression of the channel activity correlates with the expression ofgp91-phox, but not with the expression of p67-phox, p47-phox, or p22-phox
Summary
Vol 270, No 11, Issue of March 17, pp. 5909-5916, 1995 Printed in U.S.A. (Received for publication, October 18, 1994, and in revised form, December 16, 1994). The human neutrophil NADPH oxidase-associated H+ channel acts as a charge compensator for the electrogenic generation of superoxide (02). We conclude that the large subunit of the NADPH oxidase cytochrome b (gp91phox) is the arachidonate activable H+ channel of human neutrophils. A number of cytosolic factors (p67-phox, p47-phox, a small monomeric GTP-binding protein, and possibly p40-phox, a recently described protein with similarity to p47-phox) [9, 12,13,14,15] Upon activation these cytosolic factors have been shown to translocate partially to the membrane where they may interact with the cytochrome b [16].
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