Oligonucleotide probes to the 5' end of the framework 3 (FR3) gene segment detect polymorphisms of VH gene sequences encoding biologically important amino acid residues.

Abstract

In this study, we demonstrate the use of oligonucleotide probes to the most VH family-specific framework, the Framework 3 (FR3) gene segment, in the analysis of germline DNA. Compared with the hybridization of restriction enzyme-digested genomic DNA to large, cloned human VH family probes, hybridization with oligonucleotides derived from nucleotides 199 to 258 of the FR3 gene segments both yields less complex patterns and highlights polymorphic variations between individuals. The potentially important role played by amino acid residues encoded by the FR3 gene segment in influencing conformation, antigen binding and affinity of the physically proximal complementarity determining regions (CDRs) suggests FR3 sequence conservation to be biologically significant. Genomic studies combining information from both CDR and framework restriction fragment polymorphisms can prove useful in detecting specific genes and in identifying haplotypes of interest.