Surface expression of the β T cell receptor (TCR) chain in the absence of other TCR or CD3 proteins on immature T cells

T cell receptor (TCR) β genes are rearranged prior to TCR α genes. A productively rearranged TCR β gene suppresses further V_β gene rearrangement. Here we show that in β TCR transgenic mice the TCR β-chain can be expressed on the surface of immature CD4^-8^- thymocytes, but not on mature T cells, in the absence of any other known TCR chain and proteins of the CD3 complex. Analysis by NEPHGE and SDS-PAGE showed that at least some β TCR exists on the surface as a large disulfide-linked complex with unknown acidic molecules. The introduction of the β TCR gene into scid mice resulted in the expression of the β TCR on the cell surface of thymocytes and induced the expression of CD4 and CD8 co-receptors as well as transcription of the α TCR locus.