TCF-1, a T cell-specific transcription factor of the HMG box family, interacts with sequence motifs in the TCRβ and TCRδ enhancers

We have recently identified and cloned TCF-1, a T cell-specific transcription factor with specificity for the AACAAAG motif in the CD3≓enhancer and for the TTCAAAG motif in the TCRα enhancer. TCF-1 belongs to the family of transcription-regulating proteins which share a region of homology termed the HMG-box. Here, we show by gel retardation analysis that TCF-1 specifically recognizes the Tβ5 element of the TCRβ enhancer and the Tδ7 element of the TCRδ enhancer. Comparison of the sequences of all elements recognized by TCF-1 defines a consensus motif A/T A/T C A A/G A G. These observations imply that TCF-1 is involved in the control of several T cell-specific genes and might thus play an important role in the establishment and maintenance of the mature T cell phenotype.