Recently, we demonstrated that theDANgene product contains a growth- and/or a tumor-suppressive activityin vitro. In the present work, using a yeast two-hybrid system, we searched for cellular proteins that can associate with theDANgene product. A cDNA clone, termedDA41, was initially isolated from an adult rat lung cDNA library. TheDA41gene was expressed in all adult tissues examined, however, the levels of expression varied significantly among the different tissues. Like theDANgene product, the DA41 protein was similarly restricted to the cytoplasm. Sequence analysis revealed thatDA41cDNA is 2,167 nucleotides in length and contains a single open reading frame (ORF) of 582 amino acids (61,945 daltons). A homology search revealed that theDA41gene product shares no structural similarity with those filed in the data base. In a synchronous 3Y1 cell culture,DA41mRNA was expressed at a low level in quiescent cells; however, its level was significantly increased between the G1and S phases of the cell cycle. On the other hand, the expression level ofDANmRNA did not change throughout the cell cycle progression. These results suggest that the DAN-DA41 complex might play a crucial role in the regulation of the cell cycle progression.
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