Mutational analysis of the human 2B4 (CD244)/CD48 interaction: Lys 68 and Glu70 in the V domain of 2B4 are critical for CD48 binding and functional activation of NK cells

Stephen O. Mathew, Pappanaicken R. Kumaresan, Jae Kyung Lee, Van T. Huynh, Porunelloor A. Mathew

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18 Scopus citations


Interaction between receptors and ligands plays a critical role in the generation of immune responses. The 2B4 (CD244), a member of the CD2 subset of the Ig superfamily, is the high affinity ligand for CD48. It is expressed on NK cells, T cells, monocytes, and basophils. Recent data indicate that 2B4/CD48 interactions regulate NK and T lymphocyte functions. In human NK cells, 2B4/ CD48 interaction induces activation signals, whereas in murine NK cells it sends inhibitory signals. To determine the structural basis for 2B4/CD48 interaction, selected amino acid residues in the V domain of the human 2B4 (h2B4) were mutated to alanine by site-directed mutagenesis. Following transient expression of these mutants in B16F10 melanoma cells, their interaction with soluble CD48-Fc fusion protein was assessed by flow cytometry. We identified amino acid residues in the extracellular domain of h2B4 that are involved in interacting with CD48. Binding of CD48-Fc fusion protein to RNK-16 cells stably transfected with wild-type and a double-mutant Lys68Ala-Glu70Ala h2B4 further demonstrated that Lys68 and Glu70 in the V domain of h2B4 are essential for 2B4/CD48 interaction. Functional analysis indicated that Lys68 and Glu70 in the extracellular domain of h2B4 play a key role in the activation of human NK cells through 2B4/CD48 interaction.

Original languageEnglish (US)
Pages (from-to)1005-1013
Number of pages9
JournalJournal of Immunology
Issue number2
StatePublished - Jul 15 2005


ASJC Scopus subject areas

  • Immunology

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