Viertlboeck BC, Schweinsberg S, Hanczaruk MA, Schmitt R, Du Pasquier L, Herberg FW, Göbel TW.
Proc Natl Acad Sci U S A. 2007 Jul 10;104(28):11718-23. Epub 2007 Jul 2.
Institute for Animal Physiology, University of Munich, 80539 Munich, Germany.
Fc receptors are key players of the immune system that link the fine specificity of immunoglobulins and innate effector responses. Here, we describe a nonmammalian Fcgamma receptor, CHIR-AB1, a member of the leukocyte receptor complex, that binds IgY with high affinity with its single Ig domain. It is expressed on immature and mature B lymphocytes, monocytes, macrophages, and natural killer cells and harbors motifs of activating and inhibitory Fc receptors. In the absence of FcepsilonRIgamma, CHIR-AB1 can be expressed on B cells but cross-linking does not induce intracellular calcium release. In contrast, cells expressing CHIR-AB1 and FcepsilonRIgamma are triggered to release intracellular calcium upon stimulation with heat-aggregated IgY. CHIR-AB1 thus represents a primordial Fc receptor that combines features of different mammalian counterparts.