Distinct structure and signaling potential of the γδTCR complex

alphabeta and gammadelta T cells are distinguished by the clonotypic subunits contained within their TCRs. Although the alphabetaTCR has been well characterized, much less is known about the gammadeltaTCR. Here, we report that, unlike alphabetaTCRs, most gammadeltaTCRs expressed on ex vivo gammadelta T cells lack CD38. Despite this structural difference, signal transduction by the gammadeltaTCR is superior to that of the alphabetaTCR, as measured by its ability to induce calcium mobilization, ERK activation, and cellular proliferation. Additionally, the TCR complexes expressed on primary gammadelta T cells contain only homodimers; however, following activation and expansion, Fcis an element ofR1 7 is expressed and is included in the gammadeltaTCR complex. These results reveal fundamental differences in the primary structure and signaling potential of the alphabeta- and gammadeltaTCR complexes.