The C-terminal region of cellular Qin oligomerizes: correlation with oncogenic transformation and transcriptional repression.

Expression of the oncoprotein Qin induces tumors in chickens and oncogenic transformation of chicken embryo fibroblasts in culture. We performed a detailed deletion analysis of the C-terminal region of Qin (amino acids 246-451, extending from the winged helix domain to the C-terminus) and identified amino acids 246-379 as important for transformation. The same region mediates homo-oligomerization of Qin as documented in vitro by GST pulldowns and in vivo by coimmunoprecipitation. A 60 amino-acid region within the oligomerization domain is necessary and sufficient for transcriptional repression induced by Qin.