ATP-dependent chaperone which uses the energy provided by ATP hydrolysis to generate mechanical force to disassemble protein complexes (By similarity). Required for various steps of embryonic mitosis including centrosome duplication, spindle assembly, ER dynamics and cell cycle progression (PubMed:15716356, PubMed:18854144). Regulates the stability and activity of kinase air-2, a component of the chromosomal passenger complex (CPC) (PubMed:18854144). Inhibits air-2 kinase activity from metaphase to late telophase and negatively regulates air-2 stability during mitotic exit (PubMed:18854144). Controls ER transition into sheet-like structures at the onset of mitosis, possibly by regulating homotypic membrane fusion (PubMed:15716356). ATP + H2O = ADP + H(+) + phosphate Homohexamer; ATP binding induces oligomerization (By similarity). Forms a ring-shaped particle of about 12 nm diameter, that displays 6-fold radial symmetry (By similarity). Interacts (via N-terminus) with kinase air-2; the interaction is direct and inhibits air-2 kinase activity in an ATPase-dependent manner. The first ATP-binding region binds ATP with low affinity whereas the second ATP-binding region binds ATP with high affinity. RNAi-mediated knockdown causes embryonic lethality (PubMed:15716356, PubMed:18854144). The first embryonic cell divisions have mitotic spindle and chromosome segregation defects, and mitotic progression is significantly delayed (PubMed:18854144). At late telophase/G1, air-2 accumulates at the spindle midbody abnormally persisting following cleavage furrow ingression and into the next mitotic cycle (PubMed:18854144). Loss of inhibition of air-2 kinase activity (PubMed:18854144). Also, causes defects in ER dynamics characterized by a failure of the ER to form a sheet structure at the onset of mitosis and remains in large aggregates throughout mitosis (PubMed:15716356). In an air-2 (os207) mutant background, which lacks air-2 catalytic activity, restores normal mitosis and thus embryonic viability (PubMed:18854144). Belongs to the AAA ATPase family. AFG2 subfamily.