MAFA (Mast cell function-associated antigen) is a type II membranal glycoprotein, first identified on the surface of rat mucosal-type mast cells of the RBL-2H3 line. More recently, human and mouse homologues of MAFA have been discovered yet also (or only) expressed by NK and T-cells.
The intracellular domain of MAFA contains a single immunoreceptor tyrosine-based inhibitory motif (ITIM), which classifies MAFA as a member of an inhibitory receptor superfamily. The inhibitory capacity of MAFA is best defined in mast cells, where MAFA keeps in check the antigen-induced (i.e. Fc epsilon RI-induced) secretion of inflammatory mediators.
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