GERMLINE GENOMIC STRUCTURE OF THE B10.A MOUSE TCRA-V2 GENE SUBFAMILY

The number of mouse Tcra-V gene segments varies from one individual to another and is estimated to be about 100. Southern blot analysis reve aled that most of the Tcra-V are organized in clusters composed of cop ies of Tcra-V belonging to different subfamilies. We analyzed in detai l a Tcra-V subfamily and looked for new Tcra-V in order to improve the knowledge of the mouse Tcra locus organization. A series of genomic c lones derived from the B10. A mouse strain enclosing these clusters wa s used to determined the structure of all the Tcra-V2. We were able to identify ten Tcra-V2. This study showed that the Tcra-V2 can be organ ized into three structural subgroups. The distribution of the genes al ong the Tcra locus, plus their structural organization, indicates that successive duplications occurred during the processes of expansion an d contraction of the Tcra-V gene subfamilies. Several Tcra-V2 are also identical, indicating recent duplications. The most divergent Tcra-V2 differ by 7.4% nucleotides, leading to 5.2% differences in amino acid contents.