The high affinity immunoglobulin epsilon (IgE) receptor (FceRI) binds to the Fc region of IgE. A typical FceRI is a tetrameric hetero-oligomer composed of an alpha chain, a beta chain, and two disulfide-linked gamma chains []. Interestingly, human monocytes, dendritic cells and Langerhans cells express FceRI without the beta subunit, employing an alphagamma2 FceRI trimeric receptor for antigen presentation []. It has been suggested that the inclusion of beta in the FceRI produces a powerful inflammatory IgE-binding tetramer restricted to mast cells and basophils, and this plays an important role in IgE-mediated allergic reaction [].This entry represents the subunit beta of the high affinity immunoglobulin epsilon (IgE) receptor (FceRI), also known as membrane-spanning 4-domains subfamily A member 2 (MS4A2). A coding variant of MS4A2 has been associated with asthma [, ].
Membrane-spanning four-domains subfamily A (MS4A) includes B-cell-specific antigen CD20 (MS4A1), high affinity immunoglobulin epsilon receptor beta chain (MS4A2), hematopoietic-cell-specific protein HTm4 (MS4A3), and related proteins. These proteins share a similar structure with four transmembrane domains and have amino acid identities of 25-40% []. They are predominantly expressed in hematopoietic cells, but some can be found in other tissues including testis and brain [, ].MS4A1 (B-lymphocyte antigen CD20) [], MS4A2 (high affinity IgE receptor subunit beta) [, ], and MS4A4B []have been shown to have an important role in immunity.Several variants within the MS4A gene cluster have been implicated in Alzheimer's disease [].
