Helios: Proteins and Enzymes

Helios, also known as IKZF2, is a 70 kDa DNA-binding transcription regulator in the Ikaros family that contains four N-terminal C2H2-type zinc finger domains and two C-terminal zinc finger domains. Helios is expressed in developing hematopoietic and epithelial tissues and in adult T cells and thymic-derived regulatory T cells (Treg). It forms homodimers and also heterodimers with other Ikaros family proteins Ikaros, Pegasus, Eos, and Aiolos. Alternate splicing of human Helios generates a short isoform that lacks three of the the N-terminal zinc finger domains. This isoform is overexpressed in T cell leukemias where it can still dimerize with Ikaros proteins but functions as a dominant negative regulator.