Pn. Marche et al., T-CELL RECEPTOR V-ALPHA GENE SEGMENT WITH ALTERNATE SPLICING IN THE JUNCTIONAL REGION, The Journal of immunology, 151(10), 1993, pp. 5319-5327
The locus encoding mouse TCR-alpha chain includes approximately 100 Va
lpha gene segments that can be organized in about 20 structural subfam
ilies. Southern blot analysis of a T cell line derived from the BALB/c
strain, M5T, has indicated that both alpha loci were rearranged, as a
ssessed by the deletion of the delta locus, and that the Valpha gene s
egment involved in one of the rearrangements did not belong to any of
the Valpha subfamilies already described. Transcripts of TCR-alpha cha
ins from the M5T line were cloned after cDNA synthesis and anchored-po
lymerase chain reaction, revealing a Valpha gene segment of an as yet
unidentified subfamily, Valpha5T. Molecular cloning of germ-line Valph
a5T gene segments has shown that this subfamily contained two members,
one of them being a pseudogene. The two members were located to each
extremity of the alpha locus associated with a member of the Valpha13
and ValphaBWB subfamilies. Analysis of transcripts bearing the Valpha5
T gene segment in the M5T line as well as in thymocytes has revealed t
hat Jalpha are frequently absent. This is due to an alternate donor sp
lice site generated at the Valpha5T-Jalpha junction that leads to a sp
licing from the end of Valpha5T to Calpha instead of the Jalpha to Cal
pha conventional splicing. The impact of Jalpha spliced-out transcript
s on the allelic exclusion process is discussed.