Binding Mode of the Side-By-Side Two-Igv Molecule CD226/DNAM-1 to Its Ligand CD155/Necl-5
Binding mode of the side-by-side two-IgV molecule CD226/DNAM-1 to its ligand CD155/Necl-5 Han Wanga, Jianxun Qib, Shuijun Zhangb,1, Yan Lib, Shuguang Tanb,2, and George F. Gaoa,b,2 aResearch Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences (CAS), 100101 Beijing, China; and bCAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China Edited by K. Christopher Garcia, Stanford University School of Medicine, Stanford, CA, and approved December 3, 2018 (received for review September 11, 2018) Natural killer (NK) cells are important component of innate immu- CD226, also known as DNAM-1, belongs to the Ig superfamily nity and also contribute to activating and reshaping the adaptive and contains two extracellular Ig-like domains (CD226-D1 and immune responses. The functions of NK cells are modulated by CD226-D2), and is widely expressed in monocytes, platelets, multiple inhibitory and stimulatory receptors. Among these recep- T cells, and most of the resting NK cells (8, 13, 19, 20). The tors, the activating receptor CD226 (DNAM-1) mediates NK cell intracellular domain of CD226 does not contain a tyrosine-based activation via binding to its nectin-like (Necl) family ligand, CD155 activation motif, which is accepted as responsible for activating (Necl-5). Here, we present a unique side-by-side arrangement signal transduction of stimulatory molecules (13). Instead, it pattern of two tandem immunoglobulin V-set (IgV) domains transmits the downstream signaling by phosphorylation of in- deriving from the ectodomains of both human CD226 (hCD226- tracellular phosphorylation sites and subsequent association with ecto) and mouse CD226 (mCD226-ecto), which is substantially integrin lymphocyte function-associated antigen 1 (21).
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