Expression of T cell receptor gamma-chain in murine cytotoxic T cells: analysis of a highly transcribed nonrearranged gene cluster.

The murine T cell receptor gamma-gene family is organized in 4 gene clusters which encode variable, joining and constant gene segments. Because the function of the gamma-gene products is still unclear, there is great interest in functional rearrangements of these genes. We searched for new variable gamma-gene segments in the gamma 4-gene cluster. The mapping and sequencing of a supposed new variable segment of a functionally spliced transcript from a cDNA library of the cytotoxic T cell clone 3F9 was attempted. The results show that the supposed variable segment is a transcribed noncoding germline sequence 5' adjacent to the gamma 4-joining segment. With the gamma 4-constant sequence as a probe, strong signals could be shown in Northern analysis of the original T cell clone 3F9 and in other virus-specific T cell clones. Since all the T cell clones investigated did not show any rearrangement in the gamma 4-gene cluster, the observed high transcriptional activity in this region could be involved functionally or as an intermediate in T cell receptor rearrangement.