GCX-1 is a 488 amino acid transcription activator that is restricted to expression in the hypothalamus, pituitary, ovary, testis and uterus. Human reproduction is controlled by the hypothalamic-pituitary gonadal axis (HPGA) that is laid down early in fetal development. This expression pattern in the HPGA suggests that this nuclear protein is likely related to specific events in reproduction, particularly in the female. GCX-1 contains a HMG-box domain, which is commonly found in proteins that function as intercellular regulators and transcriptional co-regulators, and are found to be involved in important events such as sex determination and in the regulation of T cell differentiation. There are two isoforms of GCX-1 which are produced as a result of alternative splicing events.