Sequence and diversity of bovine T-cell receptor beta-chain genes

The nucleotide sequences of 38 T-cell receptor (Tcr) beta-chain cDNA clones which were isolated from a cDNA library (2 x 10(6) plaques) constructed from bovine peripheral blood lymphocytes were determined. Of 38 cDNA clones, 22 were rearranged and contained the functional variable (V) gene segments. These clones were tentatively divided into nine Tcrb-V gene families which correspond to the human Tcrb-V family. Among them, a Tcrb-V12 gene segment was isolated from 9 out of 22 clones, suggesting that this Tcrb-V family was expressed in the bovine peripheral blood lymphocytes. Two different constant (C) gene segments were found, and both C regions were composed of 178 amino residues. The amino acid sequences of bovine Tcrb-C regions are approximately 80%-82%, 78%, and 78% similar to those from human, mouse, and rabbit, respectively. To estimate Tcrb-V-associated restriction fragment length polymorphisms (RFLPs), Southern blot analysis was performed using liver DNAs from four bovine breeds, Holstein, Angus, Hereford, and Japanese Black. However, no significant difference was observed among genomic DNAs of Tcrb-V loci from these four breeds.