We describe six additional mutants that do not express TCR/CD3 at the cell surface.     ///    TCR/CD3 expression in these deletion mutants can be restored by transfection of TCR-alpha or TCR-beta DNA.     ///     Mutants of an untransformed T cell clone that no longer respond to TCR/CD3 stimulation have been derived using a selection procedure based on the loss of functional response to Ag. 