Enhancing and inhibitory motifs regulate CD4 activity

Mark S. Lee, Peter J. Tuohy, Caleb Y. Kim, Katrina Lichauco, Heather L. Parrish, Koenraad Van Doorslaer, Michael S. Kuhns

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


CD4+ T cells use T cell receptor (TCR)–CD3 complexes, and CD4, to respond to peptide antigens within MHCII molecules (pMHCII). We report here that, through ~435 million years of evolution in jawed vertebrates, purifying selection has shaped motifs in the extracellular, trans-membrane, and intracellular domains of eutherian CD4 that enhance pMHCII responses, and covary with residues in an intracellular motif that inhibits responses. Importantly, while CD4 interactions with the Src kinase, Lck, are viewed as key to pMHCII responses, our data indicate that CD4–Lck interactions derive their importance from the counterbalancing activity of the inhibitory motif, as well as motifs that direct CD4–Lck pairs to specific membrane compartments. These results have implications for the evolution and function of complex transmembrane receptors and for biomimetic engineering.

Original languageEnglish (US)
Article numbere79508
Issue number11
StatePublished - Jul 2022

ASJC Scopus subject areas

  • General Neuroscience
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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