Involved in mitochondrial fission. Has a partially redundant function to MDV1 in acting as an adapter protein, binding to FIS1 on the mitochondrial outer membrane and recruiting the dynamin-like GTPase DNM1 to form mitochondrial fission complexes. Plays a key role in determining the polarized localization of those DNM1 clusters that are not immediately involved in the mitochondrial fission process (By similarity). Interacts with DNM1, FIS1 and MDV1, components of the mitochondrial fission machinery. Interacts via its WD repeats with DNM1. Interacts with CCR4 and NOT1, components of the CCR4-NOT complex. It is however not a component of the 1.0 MDa CCR4-NOT core complex, but appears to be part of a less characterized, 1.9 MDa CCR4-NOT complex. Interacts with DBF2, another likely component of the 1.9 MDa complex. Interacts with SRB9 and SRB10, components of the SRB8-11 complex (By similarity). Uniformly distributed on the cytoplasmic face of the mitochondrial outer membrane. This localization is dependent on FIS1. Reorganizes to punctate structures on mitochondria, corresponding to mitochondrial constriction sites, at a late step in mitochondrial division (By similarity). Belongs to the WD repeat MDV1/CAF4 family.