bPAK-interacting exchange factor may regulate actin cytoskeleton through interaction with actin

Exp Mol Med. 2004 Dec 31;36(6):582-7. doi: 10.1038/emm.2004.75.


p21-activated kinase (PAK)-interacting exchange factor (PIX) is known to be involved in regulation of Cdc42/Rac GTPases and PAK activity. PIX binds to the proline-rich region of PAK, and regulates biological events through activation of Cdc42/Rac GTPase. To further investigate the role of PIX we produced monoclonal antibodies (Mab) against bPIX. Three clones; N-C6 against N-terminal half and C-A3 and C-B7 against C- terminal half of bPIX were generated and characterized. N-C6 Mab detected bPIX as a major band in most cell lines. C-A3 Mab recognizes GIT-binding domain (GBD), but it does not interfere with GIT binding to bPIX. Using C-A3 Mab possible bPIX interaction with actin in PC12 cells was examined. bPIX Mab (C-A3) specifically precipitated actin of the PC12 cell lysates whereas actin Mab failed to immunoprecipitate bPIX. Co-sedimentation of PC12 cell lysates with the polymerized F-actin resulted in the recovery of most of bPIX in the cell lysates. These results suggest that bPIX may not interact with soluble actin but with polymerized F-actin and revealed that bPIX constitutes a functional complex with actin. These data indicate real usefulness of the bPIX Mab in the study of bPIX role(s) in regulation of actin cyoskeleton.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / physiology*
  • Actins / metabolism*
  • Animals
  • Antibodies, Monoclonal / immunology
  • Cell Cycle Proteins / immunology
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology*
  • Cell Line, Tumor
  • Cytoskeletal Proteins / metabolism
  • Epitope Mapping
  • Guanine Nucleotide Exchange Factors / immunology
  • Guanine Nucleotide Exchange Factors / metabolism
  • Guanine Nucleotide Exchange Factors / physiology*
  • Immunoprecipitation
  • Mice
  • Protein Structure, Tertiary
  • Rats
  • Rho Guanine Nucleotide Exchange Factors


  • Actins
  • Antibodies, Monoclonal
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Guanine Nucleotide Exchange Factors
  • Rho Guanine Nucleotide Exchange Factors