AVIAN WINGED HELIX PROTEINS CWH-1, CWH-2 AND CWH-3 REPRESS TRANSCRIPTION FROM QIN BINDING-SITES

The chicken winged helix proteins, CWH-1, CWH-2 and CWH-3, were isolat ed and identified by homology cloning using the winged helix sequence of the retroviral oncogene qin as a probe. The CWH proteins act as gro wth stimulators in chicken embryo fibroblasts and in this activity res emble the Qin protein. Qin is a transcriptional regulator that functio ns as a repressor, and its oncogenic potential is correlated with the ability to repress transcription. In this communication we show that C WH proteins are localized in the cell nucleus, recognize the Qin DNA b inding site and also function as transcriptional repressors. The repre ssion activity of CWH-3 was mapped to the region of amino acids 211 to 311, a domain that is homologous to the major repression domain of Qi n.