Bau, a splice form of neurabin-I that interacts with the tumor suppressor Bin1, inhibits malignant cell transformation

Bin1 is a nucleocytoplasmic adaptor protein and tumor suppressor. A novel p rotein termed Bau was identified through its ability to interact with a reg ion of Bin1 required to inhibit malignant cell transformation by certain on cogenes. Bau is a splice form of Neurabin-I, one of two related F-actin-bin ding proteins that are proposed to link cadherin-based cell-cell adhesion s ites with the growth regulatory kinase p70(S6K). Bau lacks actin- and p70(S 6K)-binding domains found in Neurabin-I bur includes coiled-coil domains th at are part of its central domain as well as additional sequences not found in Neurabin-I. Interaction with Bin1 requires the presence of the U3 regio n which is alternately spliced in muscle cells. Bau localizes to the nucleu s and cytosol. Like Bin1, Bau can suppress oncogene-mediated transformation and inhibit tumor cell growth. We suggest that Bau may link Bin1 to the Ne urabin-I/p70(S6K) system in muscle and other cells, perhaps providing a mec hanism to influence adhesion-dependent signals which affect cell fate.