TCR-MHC docking orientation: natural selection, or thymic selection?
T cell receptors (TCR) dock on their peptide-major histocompatibility complex (pMHC) targets in a conserved orientation. Since amino acid sidechains are the foundation of specific protein-protein interactions, a simple explanation for the conserved docking orientation is that key amino acids encoded by the TCR and MHC genes have been selected and maintained through evolution in order to preserve TCR/pMHC binding. Expectations that follow from the hypothesis that TCR and MHC evolved to interact are discussed in light of the data that both support and refute them. Finally, an alternative and equally simple explanation for the driving force behind the conserved docking orientation is described.
Collins
Edward J
EJ
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, 804 Mary Ellen Jones Building, Chapel Hill, NC 27510, USA. edward_collins@med.unc.edu
Riddle
David S
DS
D000595:Amino Acid Sequence; D000818:Animals; D022801:Complementarity Determining Regions / Q000276:immunology* / Q000378:metabolism; D019143:Evolution, Molecular; D006801:Humans; D008285:Major Histocompatibility Complex / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012641:Selection, Genetic; D013950:Thymus Gland / Q000276:immunology*
D022801:Complementarity Determining Regions; D011948:Receptors, Antigen, T-Cell