Rudolph MG
Rudolph MG
Rudolph MG
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Annu. Rev. Immunol. 2006.24:419-466. Downloaded from arjournals.annualreviews.org<br />
by CAMBRIDGE UNIVERSITY on 04/04/10. For personal use only.<br />
contributing fewer conserved MHC contacts.<br />
The first crystal structures of TCRs with<br />
class I molecules led to proposals that the<br />
TCR orientation is approximately diagonal<br />
with a mean around 35◦ (36). By contrast, in<br />
the first class II complexes, the orientation<br />
was described as being closer to perpendicular<br />
(15, 18), suggesting a different binding<br />
mode between the MHC classes (81). However,<br />
we calculated this angle to be 50◦ , which<br />
is still roughly diagonal. Furthermore, the recent<br />
crystal structure determination of class<br />
I HLA-A2 in complex with the xenoreactive<br />
AHIII 12.2 TCR (20) showed a TCR/pMHC<br />
binding orientation of 67◦ , arguing against<br />
any real differences in receptor orientation<br />
between class I and class II complexes. In<br />
very low-affinity interactions (
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