Oligodendrocyte transcription factor (OLIG2) is a basic helix-loop-helix (bHLH) transcription factor encoded by the Olig2 gene. The protein is of 329 amino acids in length, 32kDa in size and contains 1 basic helix-loop-helix DNA-binding domain.[5] It is one of the three members of the bHLH family. The other two members are OLIG1 and OLIG3.