Immunoglobulin cell recognition

The cell surface additionally displays receptors responsible for cell-cell recognition [28]. Members of this class of receptors are selectins [29] that recognize specific carbohydrates from other cells in the presence of calcium. Other cell surface receptors belong to the immunoglobulin superfamily (IgSF) [30] that promote calcium-independent cell-cell adhesion. The third important class are the calcium-dependent cell adhesion molecules, the cadherins [31], which form dimers with cadherin molecules presented on the surfaces of other cells and hence promote aggregation of similar cell types. 

Many other cell-surface proteins involved in immunological recognition utilize immunoglobulin-like domains as structural elements. Immunoglobulin domains have been classified into five types, namely V (like antibody variable... 

Williams, A. F. and Barclay, A N. The immunoglobulin superfamily - domains for cell surface recognition. Annu. Rev. Immunol. 6 381-405,1988. 

The structure of MHC. In the context of antigen recognition by T cells, we are primarily concerned with class I and II MHC molecules. Class III MHC are essentially a part of the complement system. Class I molecules are made up of transmembrane heavy-chain peptide, which is noncovalently associated with the B2 microglobulin (B2m) molecule. Class II, on the other hand, is composed of two smaller transmembrane peptide chains, a and p. The peptides are arranged in domains that are of comparable size to those of the immunoglobulin molecules. 

Thymus-derived, or T, lymphocytes also have an immunoglobulin-like surface receptor linked with accessory proteins to form the T-cell receptor (TCR). There are similarities between the BCR and TCR in that the recognition part of the T receptor complex is also a dimer. In most T cells, the dimer consists of a and [3 individual peptide... 

T cells both mediate the recognition of self and also participate in the immunologic response to foreign antigens. Their surface receptors function much like the immunoglobulins that are attached to the surfaces of B cells. The T-cell receptors are a(3 disulfide-linked... 

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