Plays a role in directed cell migration by regulating the activation and subcellular location of RAC1 (Probable). Increases the presence of activated RAC1 at the leading edge of migrating cells. Required for normal organization of the cytoskeleton, including the actin cytoskeleton, microtubules and the vimentin intermediate filaments. Plays a role in endoplasmic reticulum-associated endosome fission: endosome membrane fission of early and late endosomes is essential to separate regions destined for lysosomal degradation from carriers to be recycled to the plasma membrane. Required for normal cell proliferation, cell migration, and normal formation of lamellipodia. Required for normal distribution of mitochondria within cells (By similarity). Homotrimer (By similarity). Binds F-actin. Interacts with RCC2. Interacts preferentially with nucleotide-free and GDP-bound RAC1. Interacts with VIM (via head domain) (By similarity). Colocalizes with the actin cytoskeleton in the cytosol, and especially in the cell cortex (By similarity). Colocalizes with F-actin at the leading edge of lamellipodia (By similarity). Partially colocalizes with microtubules and vimentin intermediate filaments (By similarity). Localizes to endosome membrane tubules/buds (By similarity). Morpholino knockdown of the protein causes subtle defects in mesenchymal cell migration, but no gross anatomical defects. The migration of neural crest cells towards the pharyngeal arches is altered, resulting in no clear separation between the first and second pharyngeal arch cells. Belongs to the WD repeat coronin family.