alternative products:2 series of isoforms, L and S, are produced by use of alternative promoter usage. Additional isoforms seem to exist, function:Transcriptional activator involved in T-cell lymphocyte differentiation. Necessary for the survival of CD4 (+) CD8 (+) immature thymocytes. Isoforms lacking the N-terminal CTNNB1 binding domain cannot fulfill this role. Binds to the T-lymphocyte-specific enhancer element (5'-WWCAAAG-3') found in the promoter of the CD3E gene. May also act as feedback transcriptional repressor of CTNNB1 and TCF7L2 target genes. TLE1, TLE2, TLE3 and TLE4 repress transactivation mediated by TCF7 and CTNNB1. , induction:By TCF7L2 and CTNNB1. , sequence caution:Wrong choice of frame. , similarity:Belongs to the TCF/LEF family. , similarity:Contains 1 HMG box DNA-binding domain. , subunit:Binds the armadillo repeat of CTNNB1 and forms a stable complex. Interacts with AES, TLE1, TLE2, TLE3 and TLE4. , tissue specificity:Predominantly in T-cells. Also detected in proliferating intestinal epithelial cells and in the basal epithelial cells of mammary gland epithelium. ,