ZFN pairs targeting sites within genomic loci of TCR-α and β constant region. Each exon is shown by a block. Black blocks represent coding regions. Gray columns represent noncoding regions. One ZFN pair was designed to bind exon 1 of the TCR α constant region (TRAC) and another ZFN pair binds a conserved sequence on exon 1 of the TCR β constant regions 1 (TRBC1) and 2 (TRBC2). Underlined nucleotide sequences represent the intended binding sequence of each ZFN.