HLX1 (homeobox protein HB24) is a 488 amino acid protein encoded by the human gene HLX1. HLX1 belongs to the H2.0 homeobox family and contains one homeobox DNA-binding domain. HLX1 is considered a diverged human homeodomain-containing protein known to be expressed in hematopoietic progenitors and activated lymphocytes. HLX1 is a transcription factor required for TBX21/T-bet-dependent maturation of Th1 cells as well as maintenance of Th1-specific gene expression. It is also involved in embryogenesis and hematopoiesis. Overexpression of HLX1 will cause a marked increase in activated T cells/thymocytes and interleukin-2 receptor expression. Overexpression will also impair the normal development of CD4+ T cells and will prevent the thymus from undergoing normal involution.
