TRANSCRIPTIONAL REGULATION OF THE T-CELL ANTIGEN RECEPTOR ZETA-SUBUNIT - IDENTIFICATION OF A TISSUE-RESTRICTED PROMOTER

The cell surface expression of T cell antigen receptors (TCR) is regul ated in part by the limiting synthesis of the zeta subunit. Utilizing fragments from the 5' region of the human zeta gene, two discrete regi ons that promote transcription were characterized. Both of these eleme nts are located within 125 bases of the most 3' site of transcription initiation. The more proximal (3') promoter exhibits activity in lymph oid as well as nonlymphoid cells. In contrast, the more distal (5') pr omoter element functions in a tissue-restricted fashion. The tissue-sp ecific promoter is localized to a 29-base fragment. The sequence of th is region is remarkable for a stretch of 11 consecutive purines that a re required for activity. This element constitutes the only known tiss ue-specific promoter for an invariant TCR subunit. Consistent with the unique role served by the zeta subunit in assembly of the TCR, this s tudy demonstrates that the expression of the zeta gene is regulated in a fashion distinct from other TCR components.