C-terminal SH3 domain of CrkII regulates the assembly and function of the DOCK180/ELMO Rac-GEF

J Cell Physiol. 2005 Jul;204(1):344-51. doi: 10.1002/jcp.20288.


Genetic studies in Caenorhabditis elegans identified an evolutionarily conserved CED-2 (CrkII), CED-5 (DOCK180), CED-12 (ELMO), CED-10 (Rac1) module important for cell migration and phagocytosis of apoptotic cells. Previous studies have shown that DOCK180 and ELMO comprise an unconventional bipartite Dbl homology domain-independent Rac guanine nucleotide exchange factor (Rac-GEF); but it is still unclear how CrkII functions in Rac-GEF activity. In this study, we have characterized a unique function of CrkII in phagocytosis and Rac activation mediated by the C-terminal SH3 domain, a region of CrkII that has no clear cellular or biochemical function. We found that mutations that disrupt the C-terminal SH3 domain of CrkII (CrkII-SH3-C) abrogate engulfment of apoptotic cells and impair cell spreading on extracellular matrix. Surprisingly, despite the effects on engulfment, W276K CrkII strongly potentiated Rac-GTP loading when ectopically expressed in HEK 293T cells. Contrary to the effects of the true dominant negative SH2 domain mutants (R38K CrkII) and SH3-N domain mutants (W170K CrkII) that prevent macromolecular assembly of signaling proteins, W276K CrkII increases association between DOCK180 and CrkII as well as constitutive tethering of the Crk/DOCK180/ELMO protein complex that interacted with RhoG. Our results indicate that while N-terminal SH3 of CrkII promotes assembly between CrkII and DOCK180, the C-terminal SH3 of CrkII regulates the stability and turnover of the DOCK180/ELMO complex. Studies with W276K CrkII may offer a unique opportunity to study the structure and function of the DOCK180/ELMO Rac-GEF.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • COS Cells
  • Chlorocebus aethiops
  • DNA-Binding Proteins
  • Humans
  • Kidney / cytology
  • Mice
  • Mutagenesis
  • NIH 3T3 Cells
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins / chemistry
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-crk
  • Structure-Activity Relationship
  • Transcription Factors / metabolism
  • rac GTP-Binding Proteins / metabolism*
  • rac1 GTP-Binding Protein / metabolism
  • src Homology Domains / genetics
  • src Homology Domains / physiology*


  • Adaptor Proteins, Signal Transducing
  • DNA-Binding Proteins
  • DOCK1 protein, human
  • ELMO1 protein, human
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-crk
  • SLC2A4RG protein, human
  • Transcription Factors
  • rac GTP-Binding Proteins
  • rac1 GTP-Binding Protein