Protein that interacts with the Arp2/3 complex; interaction with Arp2/3 stimulates actin filament debranching and inhibits actin nucleation; debranching activity is enhanced by Crn1p with which it forms a high affinity ternary complex (Crn1-Aim7-Arp2/3); sequence similarity to Cof1p and to human glia maturation factor (GMF); null mutant displays elevated mitochondrial genome loss