Both superantigens (SAG) and many anti-TCR monoclonal antibodies (mAb) have specificity for the V beta region of the TCR encoded by TCRBV genes. For instance the bacterial SAG staphylococcal enterotoxin E (SEE), the retroviral SAG MTV-9 and the mAb OT145 each react with human T cells expressing BV6S7. This BV gene encodes two common alleles. We found that SEE and the mAb preferentially activate T cells expressing BV6S7*1 as opposed to BV6S7*2, but Mtv-9 activates T cells expressing either allele. Thus binding to the TCR differs between the two SAGs. A mutation in the TCR HVR-4 region of BV6S7*1 (G72E), where the two BV6S7 alleles differ, indicated that HVR-4 is a component of the binding site for SEE and for the mAb OT145. BV6S7*2 has a charged E72 which may result in electrostatic repulsion of SEE, as SEE contains a similarly acidic aspartic acid residue at a TCR interaction site (204D).
TCR binding differs for a bacterial superantigen (SEE) and a viral superantigen (Mtv-9).
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L Liao, A Marinescu, A Molano, C Ciurli, R P Sekaly, J D Fraser, A Popowicz, D N Posnett; TCR binding differs for a bacterial superantigen (SEE) and a viral superantigen (Mtv-9).. J Exp Med 1 October 1996; 184 (4): 1471–1482. doi: https://doi.org/10.1084/jem.184.4.1471
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