As part of the CUL3(KBTBD6/7) E3 ubiquitin ligase complex functions as a substrate adapter for the RAC1 guanine exchange factor (GEF) TIAM1, mediating its ‘Lys-48’ ubiquitination and proteasomal degradation (PubMed:25684205). By controlling this ubiquitination, regulates RAC1 signal transduction and downstream biological processes including the organization of the cytoskeleton, cell migration and cell proliferation (PubMed:25684205). Ubiquitination of TIAM1 requires the membrane-associated protein GABARAP which may restrict locally the activity of the complex (PubMed:25684205).
