|Detection of Allergin‑1 in Human Blood-Derived Monocytes by Flow Cytometry. Human blood-derived monocytes were stained with Mouse Anti-Human Allergin‑1 APC‑conjugated Monoclonal Antibody (Catalog # FAB7638A, filled histogram) or isotype control antibody (Catalog # IC002A, open histogram). View our protocol for Staining Membrane-associated Proteins.|
Allergin-1, also known as MCA32 and c17orf60 is a 70-72 kDa member of the Ig Superfamily. It is expressed on mast cells, basophils, neutrophils, dendritic cells, B cells and monocytes, and is reported to negatively regulate allergic mediator release from mast cells. In particular, MCA32 interacts with Fc epsilon RI. Upon IgE mediated Fc epsilon RI aggregation and activation, Allergin‑1 recruits Tyr phosphatases to a Fc epsilon RI tetrameric complex, dampening IgE receptor downstream signaling and abrogating mast cell degranulation. Mature human Allergin‑1 is a monomeric type I transmembrane glycoprotein that is 324 amino acids (aa) in length. It contains two C2-type Ig domains (aa 35-118 and 123-217) in the extracellular region (aa 20-227), plus a 95 aa cytoplasmic domain that possesses two ITIM motifs. Two 40-42 kDa splice variants exist that show deletions of one of the two Ig-like domains. One isoform termed Allergin‑1S1 is missing aa 123-217, while a second isoform called Allergin‑1S2 is missing aa 33-122. It would appear that mouse Allergin-1 exists in two forms; a soluble form lacking the TM segment, and a TM form that is analogous to the human 1S1 isoform (no two Ig-like domain-containing isoform exists). Within this context (aa 20-122 plus aa 218-227 in human), human and mouse share 48% aa sequence identity.