Molecular analysis of protein interactions mediating the function of the cell surface protein CD8.

The T cell coreceptor CD8 is a cell-surface glycoprotein expressed either as a disulfide-linked homodimer of two CD8alpha monomers, or a heterodimer of CD8alpha and CD8beta. These receptors interact with ligands, such as major histocompatibility complex (MHC) class I, on the outside of the cell, with proteins inside the cell, such as the tyrosine kinase p56lck, and possibly with proteins on the same cell-surface. The molecular details describing such protein interactions can shed light on how the proteins function and the functional differences between the two forms of CD8. Crystal structures, mutational analysis, affinity measurements, and other approaches are providing those details.