The TATA binding protein (TBP) is a transcription factor that binds specifically to a DNA sequence TATA box. This DNA sequence is found about 25-30 base pairs upstream of the transcription start site in some eukaryotic gene promoters. TBP,along with a variety of TBP-associated factors,make up the TFIID,a general transcription factor that in turn makes up part of the RNA polymerase II preinitiation complex. As one of the few proteins in the preinitation complex that binds DNA in a sequence-specific manner,it helps position RNA polymerase II over the transcription start site of the gene. However,it is estimated that only 10-20% of human promoters have TATA boxes. Therefore,TBP is probably not the only protein involved in positioning RNA polymerase II. This antibody detects human TBP (~40 kDa) and mouse/rat Tbp (~35 kDa).