As. Hodtsev et al., MYCOPLASMA SUPERANTIGEN IS A CDR3-DEPENDENT LIGAND FOR THE T-CELL ANTIGEN RECEPTOR, The Journal of experimental medicine, 187(3), 1998, pp. 319-327
Superantigens are defined as proteins that activate a large number of
T cells through interaction with the V beta region of the T cell antig
en receptor (TCR). Here we demonstrate that the superantigen produced
by Mycoplasma ai arthritidis (MAM), unlike six bacterial superantigens
tested, interacts not only with the V beta region but also with the C
DR3 (third complementarity-determining region) of TCR-beta. Although M
AN shares typical features with other superantigens, direct interactio
n with CDR3-beta is a feature of nominal peptide antigens situated in
the antigen groove of major histocompatibility complex (MHC) molecules
rather than superantigens. During peptide recognition, V beta and V a
lpha. domains of the TCR form contacts with MHC and the V beta-depende
nt and is apparently stabilized by direct contacts with the CDR3-beta
region. Thus, MAM represents a new type of ligand for TCR, distinct fr
om both conventional peptide antigens and other known superantigens.