Abstract
Inhibition of gene transcription is brought about by several mechanisms. The least understood mechanism is probably silencing, the analogue to transcriptional enhancing. We provide evidence that the silencing function of the oncogene product v-ERBA or the cellular counterpart, the thyroid hormone receptor (TR, c-erbA) is located in the C-terminal part and is transferable to a heterologous DNA binding domain. Deletion analyses suggest an important role for a basic and hydrophilic amino acid stretch on both ends of the domain. In addition we show that the related retinoic acid receptor (RAR) also contains a functional silencing domain similar in size and amino acid sequence. However, the activity of this domain can be neutralized by an additional domain in the C-terminus which functions cell specifically.