The Drosophila atonal gene produces a protein with basic helix loop helix (bHLH) domains that plays an essential role in the development of the Drosophila nervous system. Mammalian atonal homolog 2 (MATH-2) is a helix-loop-helix (HLH) transcription factor that is structurally homologous to the product of Drosophila atonal gene. MATH-2 is a 337 amino acid protein with an atonal-related basic HLH domain. In mice, expression of MATH-2 takes place by embryonic day 11.5 and initially localizes to the wall of brain vesicles and in the spinal cord. It is expressed in the cortical plate and the mantle layer in the developing central nervous system, and is limited to the nervous system in adults. Adult mouse cerebrums produce a high level of MATH-2 RNA with lower levels in other neuronal tissues. Research studies suggest that MATH-2 may function as a trans-acting factor involved in the development and maintenance of the mammalian nervous system.