V(D)J RECOMBINATION CODING JUNCTION FORMATION WITHOUT DNA HOMOLOGY - PROCESSING OF CODING TERMINI

Coding junction formation in V(D)J recombination generates diversity i n the antigen recognition structures of immunoglobulin and T-cell rece ptor molecules by combining processes of deletion of terminal coding s equences and addition of nucleotides prior to joining. We have examine d the role of coding end DNA composition in junction formation with pl asmid substrates containing defined homopolymers flanking the recombin ation signal sequence elements. We found that coding junctions formed efficiently with or without terminal DNA homology. The extent of junct ional deletion was conserved independent of coding ends with increased , partial, or no DNA homology. Interestingly, G/C homopolymer coding e nds showed reduced deletion regardless of DNA homology. Therefore, DNA homology cannot be the primary determinant that stabilizes coding end structures for processing and joining.