T cell receptor (TCR)-gene-modified T cells for adoptive cell transfer can mediate objective clinical responses in melanoma and other malignancies. When introducing a second TCR， mispairing between the endogenous and introduced α and β TCR chains limits expression of the introduced TCR， which can result in impaired efficacy or off-target reactivity and autoimmunity. One approach to promote proper TCR chain pairing involves modifications of the introduced TCR genes: introducing a disulfide bridge， substituting murine for human constant regions， codon optimization， TCR chain leucine zipper fusions， and a single-chain TCR. We have introduced these modifications into our hepatitis C virus (HCV) reactive TCR and utilize a marker gene， CD34t， which allows us to directly compare transduction efficiency with TCR expression and T cell function. Our results reveal that of the TCRs tested， T cells expressing the murine Cβ2 TCR or leucine zipper TCR have the highest levels of expression and the highest percentage of lytic and interferon-γ (IFN-γ)-producing T cells. Our studies give us a better understanding of how TCR modifications impact TCR expression and T cell function that may allow for optimization of TCR-modified T cells for adoptive cell transfer to treat patients with malignancies.