The TATA-binding protein and its associated factors are differentially expressed in adult mouse tissues

We have investigated the expression levels of the TATA-binding protein (TBP ) and several TBP-associated factors (TAF(II)s) in differentiated adult mou se tissues. Immunoblots performed using monoclonal antibodies show that the re are considerable variations in the levels of TBP and many TAF(II) protei ns present in various tissues. Consequently, the relative levels of TAF(II) s and TBP vary significantly from one tissue to another. TBP and several TA F(II)s are overexpressed in both testis and small intestine, while in marke d contrast, many of these proteins, including TBP itself, were substantiall y down-regulated in nervous tissues and in the heart. These tissues do, how ever, show a high expression level of the TBP-like factor, which thus may r epresent an alternative factor for the specialized transcription program in some differentiated tissues. While there are significant variations in the levels of TAF(II)28 protein, reverse transcription-coupled polymerase chai n reaction shows similar expression of the TAF(II)28 mRNA in different tiss ues. The variations in TAF(II)28 protein levels therefore result from post- transcriptional regulatory events.