Marine and Winoto (1991) identified a common TCR regulatory element by demonstrating binding of the enhancer-binding protein GATA3 to the enhancer elements of all 4 TCR genes. GATA3
had been shown in the chicken to be an enhancer-binding protein containing a zinc finger domain. GATA3 mRNA was demonstrated by Northern blot analysis in T cells but not in B cells, macrophages, or HeLa cell lines. GATA3 was abundantly expressed in the T-lymphocyte lineage and was thought to participate in T-cell receptor gene activation through binding to enhancers. Labastie et al. (1994) cloned the human gene and the 5-prime end of the mouse gene. The 2 zinc fingers of GATA3 are encoded by 2 separate exons highly conserved with those of GATA1, but no other structural homologies between the 2 genes could be found.