Mammalian Mi-2, an auto-antigen for dermatomyositis, is known to be an adenosine 
triphosphate (ATP)-dependent nucleosome remodelling factor. The Drosophila 
homologue of Mi-2 (dMi-2) gene is located at 76D5-6 on the left arm of the third 
chromosome and is transcribed into two alternate transcripts (dMi-2a and 
dMi-2b). Both transcripts are present at high levels in the ovary and during the 
first 8 h of embryogenesis when detected by Northern blot analysis. The 
localization of protein was nuclear, which is consistent with its proposed 
function as a component of the chromatin remodelling complex. Several lines of 
recessive mutants including mutations in dMi-2 were isolated and classified into 
four different complementation groups. Four alleles of dMi-2 mutants were 
further characterized in molecular nature; dMi-2(BL1) was found to have a 
mutation in the ATP-binding motif of the ATPase domain, dMi-2(BL7) in the core 
histidine of the first plant homeodomain zinc finger and dMi-2(BL12) in a 
conserved serine in the chromodomain. On the other hand, dMi-2(BL3) did not have 
any change in the coding region. The expression pattern of dMi-2 and the 
embryonic lethal phenotypes of mutants indicate that dMi-2 is essential for 
embryonic development in Drosophila melanagaster.