Activation of the NADPH oxidase involves the small GTP-binding protein p21rac1

Nature. 1991 Oct 17;353(6345):668-70. doi: 10.1038/353668a0.


Professional phagocytes, such as neutrophils and monocytes, have an NADPH oxidase that generates superoxide and other reduced oxygen species important in killing microorganisms. Several components of the oxidase complex have been identified as targets of genetic defects causing chronic granulomatous disease. The complex consists of an electron transport chain that has as its substrate cytosolic NADPH and which discharges superoxide into the cavity of the intracellular phagocytic vacuole. The only electron transport component identified so far is a low-potential cytochrome b, apparently the only membrane component required. At least three cytosolic factors are also necessary, two of which, p67phOx and p47phOx, have been identified by their absence in patients with chronic granulomatous disease. A third component, sigma 1, is required for stimulation of oxidase activity in a cell-free system. The active components of purified sigma 1 are two proteins that associate as heterodimers, and here we report that these are the small GTP-binding protein p21rac1 and the GDP-dissociation inhibitor rhoGDI.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Enzyme Activation / drug effects
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / physiology*
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Guinea Pigs
  • Molecular Sequence Data
  • NADH, NADPH Oxidoreductases / metabolism*
  • NADPH Oxidases
  • Recombinant Proteins / pharmacology
  • Sequence Homology, Nucleic Acid
  • rac GTP-Binding Proteins


  • Recombinant Proteins
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • NADH, NADPH Oxidoreductases
  • NADPH Oxidases
  • GTP-Binding Proteins
  • rac GTP-Binding Proteins