DIVERSITY OF THE TCRA-V3 GENE FAMILY IN BALB C MICE/

Southern analysis of EcoRI-digested BALB/c Liver DNA reveals four T-ce ll receptor Tcra-V3-hybridizing DNA fragments, which are of sizes 18.0 , 12.0, 8.0, and 2.1 kilobases, respectively. These four Tcra-V3-hybri dizing genomic DNA were isolated from a BALB/c genomic library. Restri ction and Southern analysis of the genomic DNA clones showed that each of the Tcra-V3-hybridizing Eco RI DNA fragments harbors only a single Tcra-V3 gene. The DNA sequences of coding regions of the four Tcra-V3 family members were determined. These sequences show very limited div ergence from one another. Comparisons of BALB/c Tcra-V3 sequences with published Tcra-V3 sequences expressed in different strains of mice re veal substantial allelic polymorphism. Sequence similarity searches re trieved homologous rat, cattle, and human genes. The scarcity of codin g sequence divergence among members of the Tcra-V3 family and the more substantial allelic polymorphism may be general features of the T-cel l receptor V-alpha chain-encoding gene families.