This domain family is found in eukaryotes, and is approximately 110 amino acids in length. The family is found in association with pfam00178. There is a conserved PAVIVE sequence motif. Elf-1 is an immune cell specific transcription factor. It is found in T cells, B cells, megakaryocytes,and mast cells and is involved in the control of transcription for various immune proteins. These include IL-2, GM-CSF, IL-5, IL-2 receptor alpha chain, and CD4 in T cells, IgH, blk, and lyn in B cells, TdT in T and B cells, IL-3 in megakaryocytes, and SCL and Fc-epsilon-RI alpha chain in mast cells.