Table 6.
A comparison of the antigen-receptors, BCR and TCR
| PROPERTY | BCR | TCR |
|---|---|---|
| Structure | Homodimer (LH)2 | Heterodimer (αβ) |
| Combining sites | Two identical | Three different |
| Transmembrane | H-chain only | Both α and β subunits |
| Functionally expressed D-RF | One preferred RF | All three RF |
| REPERTOIRE | ||
| Germline-encoded—Germline-selected | ~40VLVH pairs anti-”CHO” | ~102 (Vα+Vβ) anti-R (MHC) |
| Germline-encoded—Somatically selected | ~1600 (402)VLVH random repertoire | None |
| Somatically encoded— Somatically selected | ~5×104 anti-Epitope | ~5×104 anti-Peptide |
| Selected role of junctional sequences (NDNJ) | Largely framework | Largely complementarity-determining |
RF = reading frame