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.