An unusual class II molecule.
An unusual class II molecule.
复制标题
一种不寻常的 II 类分子。
DOI：
10.1016/0167-5699(92)90018-3
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Peterson,PA
中科院分区：
文献类型：
--
作者：
Karlsson,L;Surh,CD;Sprent,J;Peterson,PA
The major histocompatibility complex (MHC) encodes two types of extensively polymorphic cell surface glycoproteins, called class I and class II molecules, which present peptide antigens to T cells. By virtue of their numerous allelic differences in the amino acid residues around the peptide-binding groove, class I and class II molecules can collectively accommodate a very large number of peptides. Individual T cells, however, recognize antigenic peptides in the context of only a single self-MHC molecule. This MHC restriction is imparted in the thymus during T-cell ontogeny by a process termed positive selection. Positive selection ensures that only those T cells which express receptors that can productively interact with MHC molecules present on the thymic cortical epithelium are selected for survivaP, 2.A high frequency of allelic MHC molecules within a given species probably represents an adaptation to an environment containing constantly mutating and novel pathogens. However, a large number of class I molecules are not polymorphic; these are categorized as class lb and constitute the Q, TL and HMT molecules'4. The function of class Ib molecules is largely unknown, but their lack of polymorphism suggests that they present either invariant peptides derived from self proteins or peptides from microbial proteins with properties distinct from those of self peptides. The observation that HMT molecules bind and present peptides with N-formyl-Met in the amino terminus satisfy the latter suggestion s.
