Xiao J H, Davidson I, Matthes H, Garnier J M, Chambon P
Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité 184 de Génie Génétique et de Biologie, Faculté de Médecine, Strasbourg, France.
Cell. 1991 May 17;65(4):551-68. doi: 10.1016/0092-8674(91)90088-g.
We describe the cDNA encoding the SV40 transcriptional enhancer factor 1 (TEF-1) and show that its translation initiates exclusively at an AUU codon in vivo. Cloned TEF-1, which is unrelated to other known transcription factors, specifically binds the SV40 GT-IIC and Sph enhansons. Cloned TEF-1 does not activate these enhansons in lymphoid MPC11 cells where they are known to be inactive, but represses the endogenous HeLa TEF-1 activity in vivo and in vitro. Repression is also observed with chimeras where the DNA-binding domain of the GAL4 activator replaces that of TEF-1, showing that repression results from interference/squelching. Such chimeras stimulate transcription in HeLa, but not in MPC11, cells in vivo and in HeLa cell extracts in vitro. However, high concentrations result in self-interference/squelching. These results strongly suggest that the trans-activation function of TEF-1 is mediated by a highly limiting, possible cell-specific, titratable transcriptional intermediary factor(s).
