In vitro binding of several cell-specific and ubiquitous nuclear proteins to the GT-I motif of the SV40 enhancer.
We have investigated the specific in vitro binding of nuclear proteins from several cell lines to the GT-I motif of the SV40 enhancer which overlaps with the canonical enhancer "core" homology. The binding of three proteins (GT-IA, GT-IB, and GT-IC), one of which (GT-IC) exhibits cell specificity, was detected. Competition and direct binding experiments demonstrated that the two ubiquitous proteins also bind to the GC-rich motif III from the 21-bp repeat upstream element of the SV40 early promoter and that protein GT-IA is most probably the transcription factor Sp1. The third, cell-specific protein GT-IC exhibited a high affinity for both the GT-I motif and an upstream element in the promoter of the mouse beta-major-globin gene, suggesting that this protein can act both as an enhancer and an upstream element trans-acting factor. The good correlation between the known cell-specific in vivo activity of the wild-type and mutated GT-I motif and the cell-specific binding of protein GT-IC in vitro strongly supports the conclusion that this protein is an enhancer factor. Interestingly, its cognate recognition sequence does not coincide with the core homology.
Xiao
J H
JH
Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Strasbourg, France.
Davidson
I
I
Macchi
M
M
Rosales
R
R
Vigneron
M
M
Staub
A
A
Chambon
P
P
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004742:Enhancer Elements, Genetic; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D013539:Simian virus 40 / Q000235:genetics*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; C501170:GT-IC protein, human; D009687:Nuclear Proteins; D011506:Proteins; D004262:DNA Restriction Enzymes