Functions of TCR and pre-TCR subunits: Lessons from gene ablation

Recent gene-targeting experiments have highlighted the existence of checkpoints that ensure that alpha beta T cells do not complete intrathymic differentiation if they have not attained certain landmark events. These 'proofreading' mechanisms operate by way of the pre-TCR and TCR complexes, which are sequentially expressed during T-cell development. These complexes are likely to signal via their associated CD3 subunits. By activating intracellular effecters, the CD3 subunits probably modulate gene expression profiles and drive the maturing alpha beta T cells through a precise developmental sequence.