Figure 1
From: The human immunoglobulin A Fc receptor FcαRI: a multifaceted regulator of mucosal immunity
Schematic representation of the FcαRI–FcR γ-chain complex, binding immunoglobulin A (IgA) in a 2:1 stoichiometry. Two FcαRI bind each IgA-Fc part at the Cα2 and Cα3 junction via extracellular (EC) 1. Amino acids (aa) involved in ligand-receptor binding are depicted in yellow for FcαRI–EC1 and in blue for aa in Cα2 and Cα3 of IgA (left part of figure). Deglycosylation of N58 in FcαRI-EC1 (bold) increases IgA binding. Amino acids in the transmembrane regions (TMs) of FcαRI and a FcR γ-chain homodimer, involved in complex formation, are depicted in red, whereas aa involved in signaling are shown in green. FcαRI intracellular (IC) serine 248 and 263, respectively, modulates FcR γ-chain independent interleukin (IL)-6 production and inside–out signaling. FcR γ-chain intracellular immunoreceptor tyrosine-based activation motif (ITAM) consensus (YxxLx7YxxL) is shown, as well as the disulfide bond between two cysteines at position 7 (solid line). Monoclonal antibodies and C-reactive protein recognizing different ECs of FcαRI are depicted (right part).
