Characterization of the thymus leukemia (TL) product encoded by the BALB/c T3(c) gene by DNA-mediated gene transfer. Comparison to the T13(c) product and BALB/c leukemia TL

Using DNA-mediated gene transfer, we have studied the TL protein products encoded by both the T3(c) and T13(c) BALB/c genes. Biochemically, the proteins differed in their mw. and pI points; serologically, although both molecules were recognized by TL alloantiserum, only the T13(c) protein was recognized by monoclonal TL antibodies. Interestingly, both proteins were serologically and immunochemically recognized by leukemia-specific TL.4 antiserum. The quantity of cell surface T13 was significantly greater than T3 possibly due to the less efficient splicing of T3 transcripts in the L cell nucleus; both genes directed the synthesis of cytoplasmic RNA containing an unspliced intron 3 as assessed by S1 analysis. In toto, the results suggest that T3(c) is similar or perhaps identical with the novel TL product previously identified on the surface of certain x-ray-induced BALB/c leukemias.