Transcription factor IIA is inactivated during terminal differentiation of avian erythroid cells.

Avian histone H5 and alpha A-globin genes are transcribed much more efficiently in whole cell extracts derived from immature polychromatic erythrocytes than in extracts from mature duck erythrocytes. We found that these differential activities are detectable only if assayed with promoters containing a functional TATA box. The addition of either highly purified human or recombinant yeast transcription factor IIA (TFIIA) to extracts from mature erythrocytes resulted in a significant increase in transcription from TATA-containing promoters, whereas transcription from TATA-less promoters remained unaffected. Moreover, the activity of TFIIA was found to be reduced in extracts from mature erythrocytes. These data support the proposition that inactivation of TFIIA may contribute to a general repression of gene activity in avian erythrocytes, and only those genes with alternative mechanisms of initiation complex formation continue to be expressed in these cells. In the case of the histone H5 gene, such an alternative mechanism could be mediated via the interaction between duck erythrocyte upstream stimulating factor and TFIID.