Which regions of the TCR and BCR does sCircle sequence? Home FAQ Single Cell Kits sCircle Single Cell Full-Length TCR/BCR sequencing Which regions of the TCR and BCR does sCircle sequence? sCircle® sequences the full-length V(D)J region of a TCR or BCR, including the complete V, D, and J gene segments, and part of the constant region. The kit works by circularizing full-length cDNA to bring the V(D)J region, which is at the 5′ end of the transcript, close to the cell barcode sequence at the 3′ end, so that single cell V(D)J region sequences can be obtained with short-read sequencing.