An SH3 domain and proline-rich sequence mediate an interaction between two components of the phagocyte NADPH oxidase complex.
Neutrophils possess a multicomponent NADPH oxidase system capable of producing large quantities of superoxide in a process known as the respiratory burst (1). Upon stimulation of a phagocytic cell, two cytosolic components of the oxidase, p67phox and p47phox, associate with a membrane-bound flavocytochrome b and a small GTP-binding protein to form a functional enzyme complex. Each of the Phox proteins contains two src homology 3 (SH3) domains, which are of unknown function but are potential mediators of protein-protein interactions between components of the activated oxidase. We have isolated a 47-kDa protein from lysates of differentiated HL60 cells that specifically bound to the carboxyl-terminal SH3 domain of p67phox and not to any other SH3 domain tested. This protein was identified as p47phox, and the putative SH3 domain binding site was located to a carboxyl-terminal proline-rich region. Proline-rich synthetic peptides based on this carboxyl-terminal region specifically inhibited the binding of p47phox to the carboxyl-terminal SH3 domain of p67phox, and sequential truncation defined a unique minimal sequence, which, although similar, does not match the consensus sequence defined for other SH3-binding proteins.
Finan
P
P
Yamanouchi Research Institute, Littlemore Hospital, Oxford, United Kingdom.
Shimizu
Y
Y
Gout
I
I
Hsuan
J
J
Truong
O
O
Butcher
C
C
Bennett
P
P
Waterfield
M D
MD
Kellie
S
S
D000595:Amino Acid Sequence; D002478:Cells, Cultured; D006801:Humans; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D019255:NADPH Oxidases; D010446:Peptide Fragments / Q000378:metabolism; D010586:Phagocytes / Q000201:enzymology*; D010750:Phosphoproteins / Q000378:metabolism; D011392:Proline / Q000378:metabolism*; D011485:Protein Binding; D016415:Sequence Alignment
D010446:Peptide Fragments; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D011392:Proline; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D009252:NADPH Dehydrogenase