MOLECULAR-CLONING OF A ZINC-FINGER PROTEIN WHICH BINDS TO THE HEPTAMER OF THE SIGNAL SEQUENCE FOR V(D)J RECOMBINATION

The somatic V(D)J recombination for the assembly of the Ig and TCR gen es is mediated by the recombination signal sequences (Rss) and the V(D )J recombinase. A cDNA clone was isolated from a lambdag11 expression library made from mouse thymocyte poly(A)+ RNA, using the Rss as a lig and. The deduced amino acid sequence of the putative protein, designat ed Recognition component (Rc), reveals a pair of Cys2-His2 zinc finger s followed by a Glu- and Asp-rich acidic domain. In addition, there ar e five copies of the Ser/Thr-Pro-X-Arg/Lys sequence, which are putativ e DNA binding units. The zinc finger-acidic domain structures present in Rc are also found in several enhancer binding proteins, such as tho se for the kappaB motif of the Ig kappa light chain enhancer or relate d sequences. Bacterial fusion proteins for Rc bind preferentially to t he Rss heptamer and to the kappaB motif. The dual affinities of Rc for the Rss heptamer and the kappaB motif suggest a possible link between Ig transcription and somatic recombination. The formation of multiple 'gel-shifted' DNA-protein complexes for Rc and its DNA ligand suggest s that these complexes tend to multimerize.