Leukotriene D4-induced activation and translocation of the G-protein alpha i3-subunit in human epithelial cells

Biochem Biophys Res Commun. 1996 Sep 13;226(2):413-9. doi: 10.1006/bbrc.1996.1370.


The present results show that stimulation of Intestine 407 epithelial cells with LTD4 (Leukotriene D4) triggers a rapid activation of the pertussis-toxin-sensitive Gi3-protein and a simultaneous translocation of its alpha-subunits to a crude cytoskeletal fraction. The activation of G alpha i3, which was measured as the GTP/ GDP exchange ratio, peaked about 15 s after the addition of LTD4. Western blot analyses of subcellular fractions showed that G alpha i3-subunits accumulated in the cytoskeletal fraction and decreased in the membrane fraction, and the decrease was most marked 15 s after the exposure to LTD4. None of the other pertussis-toxin-sensitive G-proteins (Gi3-Z and G alpha 0) were activated or translocated upon stimulation with LTD4. This agonist was also found to reduce the GTP/GDP exchange ratio of Gi-proteins without affecting the subcellular distribution of its alpha-subunits. These findings imply that the Gi3-protein is the pertussis-toxin-sensitive G-protein previously found to mediate several downstream LTD4-stimulated signalling events. Furthermore, the translocation of G alpha i3-subunits to the cytoskeleton and the simultaneous inhibition of G3-proteins indicate that the cytoskeleton might participate in the signalling process of human epithelial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Epithelial Cells
  • Epithelium / metabolism
  • GTP-Binding Proteins / metabolism*
  • Guanine Nucleotide Exchange Factors
  • Guanosine Diphosphate / metabolism
  • Guanosine Triphosphate / metabolism
  • Humans
  • Intestinal Mucosa / metabolism*
  • Intestines / cytology
  • Leukotriene D4 / metabolism*
  • Proteins / metabolism
  • Subcellular Fractions / metabolism


  • Guanine Nucleotide Exchange Factors
  • Proteins
  • Guanosine Diphosphate
  • Leukotriene D4
  • Guanosine Triphosphate
  • GTP-Binding Proteins