Plays a role in directed cell migration by regulating the activation and subcellular location of RAC1 (PubMed:25074804, PubMed:25925950). Increases the presence of activated RAC1 at the leading edge of migrating cells (PubMed:25074804, PubMed:25925950). Required for normal organization of the cytoskeleton, including the actin cytoskeleton, microtubules and the vimentin intermediate filaments (By similarity). Plays a role in endoplasmic reticulum-associated endosome fission: localizes to endosome membrane tubules and promotes recruitment of TMCC1, leading to recruitment of the endoplasmic reticulum to endosome tubules for fission (PubMed:30220460). 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 (PubMed:30220460). Required for normal cell proliferation, cell migration, and normal formation of lamellipodia (By similarity). Required for normal distribution of mitochondria within cells (By similarity). Involved in myogenic differentiation. Binds F-actin (PubMed:12377779, PubMed:22364218). Interacts with RCC2 (PubMed:25074804). Interacts preferentially with nucleotide-free and GDP-bound RAC1 (PubMed:25074804). Interacts with VIM (via head domain) (By similarity). Isoform 1 and isoform 2 appear as homotrimers, while isoform 3 seems to exist as monomers (PubMed:19651142). Interacts with MICAL2; this interaction recruits MICAL2 to the actin filaments (PubMed:34106209). All isoforms colocalize with the actin cytoskeleton in the cytosol, and especially in the cell cortex (PubMed:10828594, PubMed:19651142, PubMed:25074804). Colocalizes with F-actin at the leading edge of lamellipodia. Partially colocalizes with microtubules and vimentin intermediate filaments (PubMed:10828594, PubMed:19651142, PubMed:25074804). Localizes to endosome membrane tubules/buds (PubMed:30220460). Colocalizes with the thin filaments of the sarcomere and with the postsynaptic area and the junctional sarcoplasm of motor end plates. Colocalizes with the actin cytoskeleton in the cytosol, and especially in the cell cortex. Ubiquitous. The C-terminal coiled-coil domain is essential for cortical membrane localization and oligomerization. Exclusively expressed in well-differentiated myoblasts as well as in mature skeletal muscle. Belongs to the WD repeat coronin family.