Intracellular association of FGF-2 with the ribosomal protein L6/TAXREB107.

By using the yeast two-hybrid system, we identified the ribosomal protein L6/TAXREB107 as an intracellular partner for FGF-2. L6/TAXREB107 also mediates the DNA binding of the HTLV-1 transactivator Tax. In vitro binding experiments indicated that both the high-molecular-weight forms (HMW) and the 18-kDa form of FGF-2 bind to L6/TAXREB107. Deletion analysis suggested that L6/TAXREB107 has two binding sites for HMW FGF-2 and one binding site for 18-kDa FGF-2, implying that the unique N-terminal extension of the HMW FGF-2 is one of the binding domains for L6/TAXREB107. Transfection assays showed that high expression of either HMW or 18 kDa FGF-2 stimulates Tax-mediated transactivation in NIH 3T3 cells. This result suggests a possible role of FGF-2 in Tax-mediated HTLV-1 transformation as well as FGF-2 binding to ribosomes and/or their precursors. Copyright 1998 Academic Press.