Alternative splice forms of the murine T-cell receptor beta transcript in a cytotoxic T-cell line

The processing of the primary transcript of the murine T cell receptor c beta region can result in two distinct forms of protein. The optional exon, C beta O, 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 beta O exon exclusively or instead most T-lymphocytes use the C beta O exon but at low levels. We have determined that our CTL clone, B6.cl 4, produces both C beta O+ and C beta O- functional RNA transcripts. To determine the C beta O usage in this CTL clone, we coupled cDNA synthesis with the polymerase chain reaction using oligonucleotides corresponding to sequences at the V beta 14 region and sequences corresponding to C beta O or C beta 1. The data indicate that B6.cl 4 CTL clone is able to use either splice site but uses the C beta O exon at a frequency of approximately 2-3%.