The transmembrane adaptor protein TRIM regulates T cell receptor (TCR) expression and TCR-mediated signaling via an association with the TCR zeta chain

T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells. H ere we demonstrate that in mature T cells, TRIM preferentially interacts wi th the TCR via the TCR-S chains and to a lesser extent via the CD3-epsilon/ gamma heterodimer. Transient or stable overexpression of TRIM in Jurkat T c ells results in enhancement of TCR expression on the cell surface and eleva ted induction of Ca2+ mobilization after T cell activation. TRIM-mediated u pregulation of TCR expression results from inhibition of spontaneous TCR in ternalization and stabilization of TCR complexes on the cell surface. Colle ctively, our data identify TRIM as a novel integral component of the TCR co mplex and suggest that one function of TRIM might be to modulate the streng th of signals transduced through the TCR through regulation of TCR expressi on on the cell surface.