Pleiotropic changes controlled by the pre-T-cell receptor

The construction of various gene-deificient mice has facilitated the unders tanding of the role of various receptors and signaling pathways that contro l the generation of alpha beta lineage cells. A predominant role is occupie d by the pre-TCR, which not only generates large numbers of alpha beta line age cells but also controls TCR beta allelic exclusion as well as commitmen t to the gamma delta lineage versus the alpha beta lineage.