Alternative splice forms of the murine t-cell receptor β transcript in a cytotoxic t-cell line

The processing of the primary transcript of the murine T cell receptor Cβ region can result in two distinct forms of protein. The optional exon, C_βO, is appended at the 5' end of the constant region and to date has been observed at low frequencies in cDNA clones from heterogeneous populations of T lymphocyte. Because individual cell lines were not analyzed in those studies, it was not known whether small numbers of T lymphocytes use the C_βO exon exclusively or instead most T-lymphocytes use the C_βO exon but at low levels. We have determined that our CTL clone, B6.c1 4, produces both C_βO⁺ and C_βO^- functional RNA transcripts. To determine the C_βO usage in this CTL clone, we coupled cDNA synthesis with the polymerase chain reaction using oligonucleotides corresponding to sequences at the V_β14 region and sequences corresponding to C_βO or C_β1. The data indicate that B6.c1 4 CTL clone is able to use either splice site but uses the C_βO exon at a frequency of 2-3%