Updated FTP location. The ELMO1-DOCK5-Rac1 complex is a dimer of heterotrimers centered on a homodimer of the DOCK5 DHR-2 domain. We analyzed the ELMO1-DOCK5-Rac1 complex by cross-linking mass spectrometry and identified intermolecular cross-links between Rac1, ELMO1, and DOCK5.