CYTOSOLIC GUANINE-NUCLEOTIDE-BINDING PROTEIN RAC2 OPERATES IN-VIVO ASA COMPONENT OF THE NEUTROPHIL RESPIRATORY BURST OXIDASE - TRANSFER OFRAC2 AND THE CYTOSOLIC OXIDASE COMPONENTS P47(PHOX) AND P67(PHOX) TO THE SUBMEMBRANOUS ACTIN CYTOSKELETON DURING OXIDASE ACTIVATION
J. Elbenna et al., CYTOSOLIC GUANINE-NUCLEOTIDE-BINDING PROTEIN RAC2 OPERATES IN-VIVO ASA COMPONENT OF THE NEUTROPHIL RESPIRATORY BURST OXIDASE - TRANSFER OFRAC2 AND THE CYTOSOLIC OXIDASE COMPONENTS P47(PHOX) AND P67(PHOX) TO THE SUBMEMBRANOUS ACTIN CYTOSKELETON DURING OXIDASE ACTIVATION, The Journal of biological chemistry, 269(9), 1994, pp. 6729-6734
The respiratory burst oxidase is responsible for O-2(-) production in
stimulated neutrophils and B lymphocytes. Components of this oxidase i
nclude cytochrome b(558), a membrane-bound flavohemoprotein; the cytos
olic polypeptides p47(phox) and p67(phox); and one or more small G pro
teins including Rad1 Rac2, and/or Rap1A. We found that when normal neu
trophils were activated, small percentages of each of the cytosolic pr
oteins p47(phox) p67(phox), and Rac2 were transferred to the membrane
cytoskeleton. However, Rac2 was not transferred to the membrane during
activation of p47(phox)-deficient neutrophils. In normal cells, some
p47(phox) also became associated with the non-cytoskeletal portion of
the plasma membrane, but p67(Phox), Rac2, and O-2(-)-forming activity
were restricted to the cytoskeleton. Neutrophil activation also causes
the phosphorylation of multiple serines in p47(phox), The most heavil
y phosphorylated forms of p47(phox) were found solely in the membrane
cytoskeleton. These results suggest that 1) the membrane cytoskeleton
participates in respiratory burst oxidase activation, 2) the fully pho
sphorylated p47(phox) is located in the active oxidase, which resides
in the membrane cytoskeleton, and 3) Rac2 acts like a dedicated compon
ent of the respiratory burst oxidase.