Thymocyte circular DNA excised from T cell receptor alpha‐delta gene complex.

We have characterized thymocyte circular DNA excised from the T cell receptor alpha‐delta gene complex. Some delta gene clones contained unusual recombinant structures derived from V‐(D)‐J joining: (i) a reciprocal joint of direct V to J delta joining, skipping the D delta segment; (ii) a V‐D delta coding joint lacking an adjacent D delta‐J delta coding joint; (iii) a V‐ D structure containing two D delta segments. Many of the alpha gen clones contained both coding and reciprocal joints of V alpha‐to‐J alpha joining on the same structure. Most of these coding joints were out of phase; however, in one clone there was an in‐phase V‐J alpha structure. Interestingly, some alpha gene clones contained the same V gene sequence as rearranged in the delta gene clone, indicating that the same V gene family, at least in part, could be utilized for both the alpha and delta gene systems.